Refactor|libdoomsday|FS1|Zip: Reimplemented Zip with LumpIndex, Entry and LumpFile

This component now follows the high level design of FS1 Wad.

Next step: Invert the model of both FS1 Wad and Zip such that each
derives from PathTreeT with the LumpIndex as a subcomponent. It is
important to note that in the case of Wad, that the design cannot
follow the ZipArchive / Archive model exactly because Archive does
not currently allow for multiple files with the same name.
Cleanup|libdoomsday: Dumped various obsolete/unused F API routines
Cleanup|libcommon: Use de::String to extract file names from paths
Refactor|libdoomsday|FS1: Replaced F_DumpLump() with F_DumpFile()
Cleanup|libdoomsday: Removed the obsolete F_FileName(), moved F_MatchFileName()
Refactor|Audio|Client: Use de::String to concatenate base path and music/sfx paths
Cleanup|libdoomsday: Dumped the obsolete F_PrependBasePath()
Cleanup|API: Removed obsolete lumpname_t
Refactor|Client: Use de::String to compose screenshot save path
Cleanup|API: Moved filename_t to libdoomsday's sys_direc.h
Refactor|Resources|Client|Server: Use the FS1 C++ API directly
Refactor|libdoomsday|FS1: Remaining global FS1 functions are now C++
Refactor|libdoomsday|FS1: Use de::File1 instead of the opaque file1_s at API level
Refactor|libdoomsday|FS1: Use de::FileHandle instead of the opaque filehandle_s at API level
Refactor|libdoomsday|FS1|FileHandle: Removed de::FileHandle C wrapper API
Cleanup: Removed obsolete FS1 file_s/filehandle_s, cleanup
Refactor|libdoomsday|FS1: Implement pimpl in FS1 (class) with DENG2_PRIVATE, cleanup
Refactor|libdoomsday|FS1|LumpCache: Moved LumpCache impl to lumpcache.cpp plus cleanup

Its now a lot easier to see how this works...
Cleanup|libdoomsday|FS1: Minor formatting/style cleanup
Refactor|libdoomsday|FS1: Removed F_FindFileForLumpNum()