fix build and basic_window example

some restructuring due to the recent changes to usingnamespace.

also cleaned up some deprecated stuff from raylib 3.7.

- appended the contents of raylib-wa.zig into raylib-zig.zig
- using raylib functions requires `const rl = @import("raylib");`
    (and accesing the identifiers inside rl, like `rl.InitWindow`)

only the basic_window example was updated, and it looks like it crashes
on keyboard inputs.

many thanks to @nektro :)

examples/shaders/rlights.zig

@@ -1,126 +0,0 @@
-// This is a zig port of rlights.h by Ryan Roden-Corrent (rcorre).
-// The original notice follows:
-//
-// *********************************************************************************************
-//
-//    raylib.lights - Some useful functions to deal with lights data
-//
-//    CONFIGURATION:
-//
-//    #define RLIGHTS_IMPLEMENTATION
-//        Generates the implementation of the library into the included file.
-//        If not defined, the library is in header only mode and can be included
-// in other headers or source files without problems. But only ONE file should
-// hold the implementation.
-//
-//    LICENSE: zlib/libpng
-//
-//    Copyright (c) 2017-2020 Victor Fisac (@victorfisac) and Ramon Santamaria
-// (@raysan5)
-//
-//    This software is provided "as-is", without any express or implied warranty.
-// In no event will the authors be held liable for any damages arising from the
-// use of this software.
-//
-//    Permission is granted to anyone to use this software for any purpose,
-// including commercial applications, and to alter it and redistribute it freely,
-// subject to the following restrictions:
-//
-//      1. The origin of this software must not be misrepresented; you must not
-// claim that you wrote the original software. If you use this software in a
-// product, an acknowledgment in the product documentation would be appreciated
-// but is not required.
-//
-//      2. Altered source versions must be plainly marked as such, and must not
-// be misrepresented as being the original software.
-//
-//      3. This notice may not be removed or altered from any source
-// distribution.
-//
-// *********************************************************************************************/
-
-const std = @import("std");
-usingnamespace @import("raylib");
-
-const max_lights = 4;
-
-pub const Light = struct {
-    type: LightType,
-    position: Vector3,
-    target: Vector3,
-    color: Color,
-    enabled: bool,
-
-    // Shader locations
-    enabledLoc: i32,
-    typeLoc: i32,
-    posLoc: i32,
-    targetLoc: i32,
-    colorLoc: i32,
-};
-
-// Light type
-pub const LightType = enum { directional, point };
-
-var lightsCount: u32 = 0;
-
-fn getShaderLoc(shader: Shader, name: []const u8) !i32 {
-    // TODO: Below code doesn't look good to me,
-    // it assumes a specific shader naming and structure
-    // Probably this implementation could be improved
-    // (note from original C implementation, I don't have a better idea)
-    var buf: [32]u8 = undefined;
-    const key = try std.fmt.bufPrintZ(buf[0..], "lights[{}].{s}", .{ lightsCount, name });
-    return GetShaderLocation(shader, key);
-}
-
-// Create a light and get shader locations
-pub fn CreateLight(typ: LightType, position: Vector3, target: Vector3, color: Color, shader: Shader) !Light {
-    if (lightsCount >= max_lights) {
-        return error.TooManyLights;
-    }
-
-    const light = Light{
-        .enabled = true,
-        .type = typ,
-        .position = position,
-        .target = target,
-        .color = color,
-
-        .enabledLoc = try getShaderLoc(shader, "enabled"),
-        .typeLoc = try getShaderLoc(shader, "type"),
-        .posLoc = try getShaderLoc(shader, "position"),
-        .targetLoc = try getShaderLoc(shader, "target"),
-        .colorLoc = try getShaderLoc(shader, "color"),
-    };
-    UpdateLightValues(shader, light);
-
-    lightsCount += 1;
-
-    return light;
-}
-
-// Send light properties to shader
-// NOTE: Light shader locations should be available
-pub fn UpdateLightValues(shader: Shader, light: Light) void {
-    // Send to shader light enabled state and type
-    SetShaderValue(shader, light.enabledLoc, &light.enabled, @enumToInt(ShaderUniformDataType.SHADER_UNIFORM_INT));
-    SetShaderValue(shader, light.typeLoc, &light.type, @enumToInt(ShaderUniformDataType.SHADER_UNIFORM_INT));
-
-    // Send to shader light position values
-    const position = [3]f32{ light.position.x, light.position.y, light.position.z };
-    SetShaderValue(shader, light.posLoc, &position, @enumToInt(ShaderUniformDataType.SHADER_UNIFORM_VEC3));
-
-    // Send to shader light target position values
-    const target = [3]f32{ light.target.x, light.target.y, light.target.z };
-    SetShaderValue(shader, light.targetLoc, &target, @enumToInt(ShaderUniformDataType.SHADER_UNIFORM_VEC3));
-
-    // Send to shader light color values
-    const color = [4]f32{
-        @intToFloat(f32, light.color.r) / 255.0,
-        @intToFloat(f32, light.color.g) / 255.0,
-        @intToFloat(f32, light.color.b) / 255.0,
-        @intToFloat(f32, light.color.a) / 255.0,
-    };
-    SetShaderValue(shader, light.colorLoc, &color, @enumToInt(ShaderUniformDataType.SHADER_UNIFORM_VEC4));
-}