Added ignores for Intellij Idea files/project directory
Changed BoundedPriorityQueue to use a internal queue variable
 The heappush function in heapq.py starts by calling append on the queue, causing endless recursion. This doesn't happen in cpython because it's using a C implementation, but eg. pypy uses the python version.
Merge remote-tracking branch 'upstream/master' into develop
Merge remote-tracking branch 'upstream/develop' into develop
Merge remote-tracking branch 'upstream/develop' into develop
Merge remote-tracking branch 'upstream/develop' into develop
Merge remote-tracking branch 'asbupstream/develop' into use-internal-queue

Conflicts:
	.gitignore
Added __len__ and __getitem__ methods
Merge branch 'use-internal-queue' into develop
Merge pull request #47 from alep/develop

Add documentation regarding arc concistency and making a problem binary constraint with hidden variables.
Merge pull request #48 from fjcapdevila/develop

Make BoundedPriorityQueue use internal heap instead of subclassing from list
Merge remote-tracking branch 'upstream/develop' into develop
mk_hidden_variable_representation returns new variables
Merge branch 'binary-constraints-tests-and-variables' into develop