Various backend improvements.

- Rewrite windows loader to use standard Toolhelp32 snapshots instead of
  hardcoding internal Windows structures with GetPebAddress.

- Refactor file-finding code to find_files_list in utils.h.

- Add test for existence of game_data.ini.

- Rewrite read_* functions in favor of passing void * pointers directly
  to read_raw.

- Move enumerate_vector and write_int to DFInstance from the
  platform-specific classes.

- Use more C++ casts instead of C-style casts.
Add windeployqt.sh, instructions to BUILDING.rst.

windeployqt.sh automatically traces DLL dependencies and copies the
appropriate files to the build directory for manual execution or packaging.
Use weak symbols for process_vm_* functions.

This allows DT to run on pre-2.15 glibcs.
Merge branch 'gitignore' into DF2014
Merge branch 'share' into DF2014
Merge branch 'travis' into DF2014
Merge branch 'weak' into DF2014
Merge branch 'windows' into DF2014

Conflicts:
	src/dfinstancelinux.cpp