Implement, test and benchmark findMin and findMax.

--HG--
extra : rebase_source : 7c648ec2765b8df88425c078e1ecb44659d792b9
extra : histedit_source : e016c92022737f29bab58861e0cbabec489eee7c
Mention what a crit-bit tree *is* (thanks, reddit!)
Implement deleteMin, deleteMax, deleteFindMin, deleteFindMax

--HG--
extra : rebase_source : f62ee347ea5b6de15c4f288d67827d96677c5b1d
extra : histedit_source : 5a694e0e358baea7f2e2aaf02313fe4e2335a06f
.gitignore: ignore Cabal sandbox dir and config file.
Formatting.
Small tweaks to 'maskLowerBits'.

Intention is to make it more clear what is going on.
Increase dependent cabal version to avoid the bug of cabal

According to https://github.com/haskell/cabal/issues/1045, test suites
don't contribute to cabal_macros.h MIN_VERSION_pkg pragmas in the prev
ious version of cabal. This bug is fixed in cabal 1.16. However, haske
ll-platform 2012.4.0 comes with cabal 1.14
Clarify a comment.

From my reading of the code, this is how things actually work.
Pull leftmost/rightmost functions to top level.

--HG--
extra : rebase_source : 07174380cc9c7a0a09bf18cd707a44cc60be0313
extra : amend_source : 35afdf933724db2f02ad58919e302aeb4c6d6650
extra : histedit_source : e28d53fdea7cb33c695b84f894723541c214dd6b
Trailing whitespace.
Merge pull request #11 from 23Skidoo/small-fixes

Small fixes
Implement 'toAscList' and 'toDescList'.
A little reformatting
Better tests for deleteFindMin / deleteFindMax
Merge pull request #12 from 23Skidoo/asc-desc-list

Implement 'toAscList' and 'toDescList'.
Merge
Merge pull request #10 from MnO2/master

Increase dependent cabal version to avoid the bug of cabal
Merge
Merge remote-tracking branch 'upstream/master'

Conflicts:
	Data/CritBit/Core.hs
	Data/CritBit/Tree.hs
	benchmarks/Benchmarks.hs
	tests/Properties.hs