Use FREE macro for freeing colors

This macro will set the colors to NULL which avoids a double free on
reload when colors that were unconfigured become configured.

fixes #1299
Merge branch 'fix-i3bar-colors'
Merge branch 'master' into next
Make absolute floating move work with criteria

Make commands of type `move [window|container] [to] [absolute] position
<px> [px] <px> [px]` work with command selection criteria.

fixes #1301