Mac OS X: use IPV6_V6ONLY

As of 10.8, Mac OS X seems to behave more like Linux in the way
that IPv6 and IPv4 binding interact.

Closes PR 13193
fix submodule declarations nested in phases > 1
adjust check syntax to deal properly with submodules at non-zero phases

Thanks to Matthew for sorting this out.

(Also removed a bunch of line-ended space chars since git
yelled at me.)
fix for `syntax-local-value/immediate'

The source locaiton on the second result was mangled.

Closes PR 12477
pretty-format returns a String, not Void
typo in test suite
add 'values' to plai/gc2/mutator language
fix plai/gc2/mutator for the case where a lambda-bound
variable is shadowing something
IN PROGRESS: working on syntax error messages for 2d
Argh, sorry again.

Revert "IN PROGRESS: working on syntax error messages for 2d"

This reverts commit 04ada6674156d1595a3bbcf5f3ed1b4504c44813.
Removing the planet2 name from the code
Fixing broken rackunit tests
Fix props order.
Undo no-op change.

As discussed:
  http://lists.racket-lang.org/users/archive/2013-March/056907.html
polarity flip in type error messages
Redex: parameterized disequations

refactor the pattern unifier and tests to handle
disequations with parameters correctly
Redex: rework metafunction compilation/search for parameters
Redex: corrections for disequations in generator

- handle parameters correctly when simplifying disequations
- rework term generation/disequation checking for parameters
- fix define-extended-metafunction w/r/t the above
Redex: remove some now extraneous code
Added tests for blame object source locations being srcloc structs.