Static literal hash

[kddnewton]

Switch from binary search to hash lookup.

Before:

irb(main):001> measure
TIME is added.
=> nil
irb(main):002> code = 1000000.times.to_h{[_1,1]}.inspect;
processing time: 0.323862s
irb(main):003> Prism.parse_success? code
processing time: 0.312201s
=> true
irb(main):004> code = 1000000.times.reverse_each.to_h{[_1,1]}.inspect;
processing time: 0.329255s
irb(main):005> Prism.parse_success? code
processing time: 85.215507s
=> true
irb(main):006>

After:

irb(main):001> measure
TIME is added.
=> nil
irb(main):002> code = 1000000.times.to_h{[_1,1]}.inspect;
processing time: 0.327138s
irb(main):003> Prism.parse_success? code
processing time: 0.329897s
=> true
irb(main):004> code = 1000000.times.reverse_each.to_h{[_1,1]}.inspect;
processing time: 0.339055s
irb(main):005> Prism.parse_success? code
processing time: 0.316168s
=> true
irb(main):006> 

Fixes #2495