More Functional Parsing DSL API.

[bd82]

Some of this was suggested in the past by @Zumbala
#215 (comment)

All the parsing DSL methods should return a value.
Currently this is only true for OR and CONSUME
but it should also be applied to:

• OPTION
  • Return the value of the implementation function or undefined? if the option was not taken?
• MANY[_SEP]
  • Return an array of the values return by each iteration of the implementation function. An empty array if no a single iteration happened.
• AT_LEAST_ONE[_SEP]
  • Same as MANY

The _SEP variants should return two arrays, one of the separator tokens and one of the values.

[bd82]

This may have a slight performance impact, should be measured.

[bd82]

Performance impact was very small and was mostly mitigated with some optimizations.
worst case measured was about ~4-5% which can be reduced to ~2% if the *_SEP syntactic sugar methods
are not used.

[bd82]

Breaking Changes:

This change broke a few APIS:

• OPTION now returns the value of the inner grammar implementation or undefined otherwise instead of boolean.
• The *_SEP methods now return an object made up of two arrays, separators and values instead of a single array of separators.