Change name of _build_range to be more explicit

Splitting the _build_range functions into 2 functions: chpl_build_bounded_range
and chpl_build_unbounded_range. This is for the upcoming anonymous range
iteration optimization where we want a clean way to find fully bounded ranges
early in compilation.

Added a chpl_ prefix instead of keeping the single underscore since that's the
direction we want to move with internal functions.
Update errors for malformed param ranges

Add the fact that param ranges must be bounded to the error messages
Missed adding an ==0 for strcmp
Need to add an error case for invalid types on partially bounded ranges

Since all the range builders used to have the same name, and the partially
bounded ranges and fully bounded ranges took the same number of parameters, the
generic error case applied to unbounded ranges as well. It no longer does since
the names are different so adding an error case.
Split up builders for unbounded ranges

Instead of having:
 - chpl_build_bounded_range
 - chpl_build_unbounded_range

we now have:
 - chpl_build_bounded_range
 - chpl_build_partially_bounded_range
 - chpl_build_unbounded_range

It seemed worthwhile to split the builders up further to be able to identify
partially bounded vs completely unbounded ranges. It doesn't feel worthwhile to
split up the partially bounded into low and high bounded (though it'd be easy
to do in the future if we change our minds.)

If you have a range like "1.." it feels more natural to call it a partially
bounded range instead of an unbounded range. I suppose it could be called a
partially unbounded range, but that feels strange. Unbounded implies ".." to
me, so it makes sense to split out the builders at the very least to avoid any
confusion.
Update REGRESSIONS for 09-12-2014
Update REGRESSIONS for 15-12-2014
Merge pull request #1012 from Kyle-B/kb-regressions-12-2014

Regressions update for the week of 08-12-2014
Merge pull request #1003 from ronawho/change_build_range_signature

Change name of _build_range to be more explicit

[ok'd and suggested by @bradcray]

Split _build_range into:
 - chpl_build_bounded_range
 - chpl_build_partially_bounded_range
 - chpl_build_unbounded_range

This was motivated by the upcoming anonymous range construction elimination
work. I need a way to determine if a range is fully bounded immediately after
parse time. The checks that I was doing were restrictive and ugly so this
allows me to simply check for the appropriate builder based on name.

Added the chpl_ prefix to the builders since we're trying to move away from a
single underscore to indicate a Chapel-reserved word.

Also updates error messages for malformed param for loops to indicate that
param for loops only work on bounded ranges.