Better shift-reduce disambiguation about parglare

[igordejanovic]

Maybe this could be unified with #42 so that the same syntax would be used.

MyProduction: some terms and non-terms {>term1, >term2, shift};

>term1 would mean that this production should be reduced if lookahead is term1. shift as default could be implied if > is used. In the case of non-terminals definition this would enhance static disambiguation during LR table calculation, while for terminal definition it would be used dynamically.

This could be used to resolve reduce-reduce conflicts like:

MyProduction: .... {>SomeOtherNonTerminalRule};

This could mean that in case of R/R conflict with SomeOtherProduction, MyProduction reduction would take place. This should be defined per production and with lookahead so the full syntax would be:

MyProduction: .... {>SomeOtherNonTerminalRule[3]:term1};

Where SomeOtherNonTerminalRule[3]:term1 is the third production defined in the rule SomeOtherNonTerminalRule when lookahead is term1. Production index as well as lookahead may be optional. If not specified it would mean any.