tower ast: explicitly add ivory types to the AST.
tower ast: expose time pretty print function for aadl backend.
emitter: put proc name in AST (for use in aadl backend).
tower time: put us pretty-print function in a petter location.
tower: smart constructors for Milliseconds and Microseconds.
Initial AADL generator.
tower-aadl: major refactoring, front-end, test.
tower-aadl: git ignore.
Merge remote-tracking branch 'origin/tower-9' into tower-aadl
tower-aadl: tweak build, integrate with top-level build.
readme: hyperlink to travis. Currently tower-9 branch.