Bump version number and add release notes.
Fix selectors matching against arrays containing subdocuments.

This is a 0.5.5 regression (with the new selector compiler): the new compiler
handled selectors with "a.b.c" reasonably well if the "c" level contained an
array but not if the "a" or "b" levels did.

This also implements mostly-Mongo-compatible behavior for sorting when arrays
are involved; this is not an 0.5.5 regression, since the old compiler did not
get this right.
Fix override for icon-white

CSS Selector was not matching => wrong image loaded in certain cases
Merge branch 'release-0.5.6'
Merging master to devel for 0.5.6
Fix #604: input with name="id" in form
Better UI for in-browser test runner
Reduce unnecessary Mongo polling.

Specifically, updates and removes that specify a specific _id, and all inserts,
should not require live queries that specify a specific different _id to poll.

This involves changing the InvalidationCrossbar matching semantics. I suspect
that a future version of the InvalidationCrossbar may want the old semantics, if
the notifications it is receiving are more oplog-driven than command-driven, but
this will work for now.

Also, make the O(1) optimization on minimongo remove("id") actually work.
Previously it was declawed by the fact that Meteor.Collection.remove normalizes
to {_id: "id"}.