Pash-Project/Pash — pull request #181 by ygra (2013-11-23 15:43:52+00:00)
Title: Implemented unary minus for numbers.

This is a little tricky when the respective minimum values of a two's
complement integer are concerned, as the digits themselves are parsed as
the larger type (long or decimal in that case) and we have to make sure
that the final result is a literal of the smaller type.