Add benchmark pidigits

Memory usage is quite high
Properly highlight constants in :pprint
Let IDESlave run :pprint
Some comments for pidigits
Merge pull request #1550 from david-christiansen/pprint-command

Improvements to :pprint - constant highlighting and IDE support
Merge pull request #1552 from Helkafen/benchmarks

Benchmarks
javascript: added LFNegate primitive
Merge pull request #1555 from raichoo/master

javascript: added LFNegate primitive