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

pm_shared/pm_movevars.h

@@ -1,6 +1,6 @@
 //========= Copyright (C) 1996-2002, Valve LLC, All rights reserved. ============
 //
-// Purpose: 
+// Purpose:
 //
 // $NoKeywords: $
 //=============================================================================
@@ -21,8 +21,8 @@ struct movevars_s
 	float	accelerate;        // Acceleration factor
 	float	airaccelerate;     // Same for when in open air
 	float	wateraccelerate;   // Same for when in water
-	float	friction;          
-	float	edgefriction;	   // Extra friction near dropofs 
+	float	friction;
+	float	edgefriction;	   // Extra friction near dropofs
 	float	waterfriction;     // Less in water
 	float	entgravity;        // 1.0
 	float	bounce;            // Wall bounce value. 1.0
@@ -35,13 +35,13 @@ struct movevars_s
 	float	rollangle;
 	float	rollspeed;
 	float	skycolor_r;			// Sky color
-	float	skycolor_g;			// 
+	float	skycolor_g;			//
 	float	skycolor_b;			//
 	float	skyvec_x;			// Sky vector
-	float	skyvec_y;			// 
-	float	skyvec_z;			// 
+	float	skyvec_y;			//
+	float	skyvec_z;			//
 	int	features;		// engine features that shared across network
-	int	fog_settings;	// Global fog settings (packed color+density) 
+	int	fog_settings;	// Global fog settings (packed color+density)
 	float	wateralpha;	// World water alpha 1.0 - solid 0.0 - transparent
 	float	skydir_x;		// skybox rotate direction
 	float	skydir_y;		//