int identifier assigned to the game directory. Remember that main
<install_dir>/game1 and the unix <userdir>/game1 have the same id.
The id starts as 1 for the first data1 directory. For every new
directory, the value is the left-shifted version of the previous
one. Made COM_FindFile() to accept a path_id pointer argument
and storing the id in it if it isn't NULL. Made COM_OpenFile(),
COM_FOpenFile() and all COM_Load* functions to accept a path_id
pointer argument similarly. Adjusted callers accordingly.
git-svn-id: http://svn.code.sf.net/p/quakespasm/code/trunk/quakespasm@370 af15c1b1-3010-417e-b628-4374ebc0bcbd
