Fixed GDC pass-to-linker flag (missing space after -Xlinker).
Don't call multilib_is_native_abi for D application ebuilds (DLANG_PACKAGE_TYPE=single), because we don't need/import that function there.
Force ldc2 -oq flag in __dlang_use_build_vars() to allow separate compilation when multiple modules with the same file name exist.
Added function to compile D applications in a compiler agnostic way.
Versions, import paths can be passed to both the application build function and the shared library build function.
The "debug" use flag, if used by an ebuild will be reflected by raising the debug level to 1 during compilation.
Added dub 0.9.21 ebuild. Fixes #1.