Add compiler flag -Dstage3d

to successfully build on other platforms. not only flash
Merge pull request #61 from disjukr/master

Modified `project.nmml` on stage3d sample
set -D no-pattern-matching to avoid completely new switch behavior that breaks pretty much any significant existing code and requires completely rewriting libraries. maybe at some point we can enable pattern matching by default, but currently it's not as simple as other haxe3 updates such as get/set, removing commas, rethinking static inlines, etc. Also (maybe just for now) add -D log to the compiler call when -debug is in place. It appears to no longer be defined by default. Maybe there is another way and that one can be removed, but it makes logging on large-scale projects stop working and for now I believe it should be in place by default until other accommodations can be made.
Define "haxe3" in NMML, for easier referencing if including version-specific Haxe flags

Removed the no-pattern-matching and log defines. The next version of NME is a clean break, targeting only Haxe 3. Although these defines are probably convenient for porting older libraries easier, I think this should be (at best) a project-specific decision for the developer, or (at worst) added in an include.nmml for the library.

The big shift for the switch() statement is instead of MyEnum.VALUE, you use VALUE in the case statements. The second is that only static runtime values appear to be eligible for a Haxe 3 switch, so sometimes it may make sense to use if() statements instead. This can cause bumps, but I think this needs to be up to the user to disable or not.