array slicing by range or another array; @list[ $a .. $b ] and @list[ @a ] should work now.
simple expressions as range operands wasn't working; "1 .. ($n-1)" works now, but "1 .. $n-1" is still broken.
test for expressions as range operands
helper method to parse expressions with any parser combinator
few more problems from "99 problems" series.
Merge pull request #84 from MoeOrganization/prakashk/array-slice-and-stuff

Array slicing by range/another array and other stuff