Trim all trailing whitespace

The `.editorconfig` file in this repo is configured to trim all trailing
whitespace regardless of whether the line is modified.

Trims all trailing whitespace in the repository to make the codebase easier
to work with in editors that respect `.editorconfig`.

`git blame` becomes less useful on these lines but it already isn't very useful.

Commands:

```
find . -type f -name '*.h' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
find . -type f -name '*.c' -exec sed --in-place 's/[[:space:]]\+$//' {} \+
```

public/matrixlib.c

@@ -635,7 +635,7 @@ qboolean Matrix4x4_Invert_Full( matrix4x4 out, const matrix4x4 in1 )
 	r[3][4] =	0.0f;
 	r[3][5] = 0.0f;
 	r[3][6] = 0.0f;
-	r[3][7] = 1.0f;	
+	r[3][7] = 1.0f;
 
 	if( fabs( r[3][0] ) > fabs( r[2][0] ))
 	{