Merge: Clean generated parser
This series reduce the size of the generated parser.
* First, factorize generated clones (the first commit)
* Second, reduce inlining in the grammar (the other commits)
This was a tidy process because each slight modification in the grammar yields to numerous conflicts often
difficult to understand. But the results worth the pain:
Time of `nitg nitg.nit`
before: 0m10.784s
after: 0m7.956s
gain: 26%
Number of subclasses of `ReduceAction`
before: 780
after: 376
gain: 52%
Pull-Request: #388
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>