v0.3 fix and new features
New features:
- can now specify directly a single dcg instead of a list with a single
item - add a generator//1 rule for regenerating automatically the ninja build
file when the prolog build file changes - add a seq//1 rule for sequential build rules
- add a write_build/1 predicate for writing the ninja build file
Fixes:
- deps//1 can generate '<not_found>' atom