Merge pull request #196 from p0nce/master

toNativeString() now returns "." on Windows for relative empty paths whe...
Let "dflags" specified for build types also be affected by build requirements.
Add unit test for Path.toNativeString() w.r.t. endsWithSlash() and fix Path().toNativeString() on Posix.
Add "release-nobounds" build type. Fixes #141.
Implement individual building of dependencies.
Improve error message when removing a cached package fails due to a missing installation journal.
Implement a first version of a proper build ID computation.

Currently, the build ID is built from a few options that are not strictly necessary to be included (build flags and options) - it would be sufficient to just include the build settings introduced by the selected build type (and would reduce the number of build cache folders).
Fix computation of build settings necessary for linking to library dependencies.
Fix compiler errors on DMD 2.063.2.
Fix build settings used for dependencies that are referenced multiple times and remove the Mono-D generator.