dsc v0.9.0

In addition to the usual various improvements made in every Flame release, Flame v0.9.0 comes bundled with an alias-analysis based -foptimize-new-struct pass. It will apply in-place construction quite aggressively, and is enabled by default starting at -O2. To the best of my knowledge, this optimization is both more correct (see this Roslyn issue) and usually more aggressive than the equivalent optimizations in csc and mcs.