Implements new local file search paths for various game formats.

[CCHyper]

Closes #87, Closes #94, Closes #513, Closes #514, Closes #515

This pull request implements various new systems to allow users, mods and mod developers to use subdirectories to store game files.

-- Local CD Files The -CD command-line argument from Red Alert has been implemented. This allows the user to define an additional local search directory for placing the contents of the game CD's.

-- File Loading The following search directories have been added (in order of priority, root folder is still highest); INI - .INI control files and .TXT files. MIX - .MIX archive files. SHP - .SHP image files and .PAL palettes. AUD - Any/all .AUD files. PCX - .PCX image files. MAPS\MULTIPLAYER - Multiplayer .MAP and .MPR maps, .PKT files. MAPS\MISSION - Mission .MAP scenarios. MAPS - Both Multiplayer and Mission maps, .MAP and .MPR, .PKT files. MOVIES - .VQA video files. MUSIC - .AUD theme files. SOUNDS - .AUD sound effect files.

Also, for adding CD content locally; TS1, CD1, and GDI - Contents of the GDI CD (must also contain TS1.DSK). TS2, CD2, and NOD - Contents of the NOD CD (must also contain TS2.DSK). TS3, CD3, and FIRESTORM - Contents of the Firestorm CD (must also contain TS1.DSK).

In addition to this, three system environment variables have been added for you to define if you use version control or use a cloud storage system that syncs to your PC. For more on adding environment vars: https://superuser.com/questions/949560/how-do-i-set-system-environment-variables-in-windows-10

TIBSUN_MOVIES - .VQA video files. TIBSUN_MUSIC - .AUD theme files. TIBSUN_FILES - Any and all formats the game supports.