Bridge AppIds are now AppId_t instead of ints.

1. Plus a bit of syntax cleanup.
Core now uses dynamic Init/Shutdown symbols.

1. Which breaks everything else, FYI.
2. Reworked SteamAPIContext construct/prepare to handle dynamically
loading libsteam_api.so.
3. Added a macro to help with making dynamic API calls.
Converted SteamClient to load dynamically.
Converted two more minor API calls to dynamic.
Updated callback to use dynamic API symbols.
Updated Bridge to no longer link to steam_api.

1. libsteam_api.so is now handled entirely though dl*, and is expected
to be found in the root SteamBridge directory.
2. Updated winemaker script and the Makefile accordingly.  Bridge still
uses the SteamAPI headers, of course.
Renamed Bridge directory again.

1. Because it's 2014, and readable names are IN.
2. Updated core to better reflect the filenames set by the install script.
3. Renamed install.sh to setup.sh, at least for now.
4. Setup.sh now checks for and copies steam_api_bridge.dll.so to the
right place.
Fixed potential bug with creating extra folders.

1. Setup was creating all parent directories for the SteamBridge root
directory.  This is undesirable, as these folders will exist if Steam
is properly installed.  If it's not, it'll create them (which is bad,
as it may conflict with Steam being installed for real).
Updated documentation.