Several changes:

- Fix anf of if branches
- Fix lots of bugs in boilerplate for parsing
- Add lots of symlinks for builtin libraries
- Bash script for compiling built-in libraries
- Shims for moving from old location style to new location style
- Minor bugfix in cmdline.rkt for a missed else case
- Desugar shared: in data definitions
- Add substring and repeat to strings
Merge branch 'nwo' of github.com:brownplt/pyret-lang into nwo