Cleanup: nice bool return value from ed_node_link_conditions function instead of using the space pointer for this.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61184 954f8c5b-7b00-dc11-b283-0030488c597c
Fix for node link highlighting not getting reset if a transform operator is cancelled and the node removed. Pass the 'test' option in node link insert testing on to the conditions function, so that at least the highlight flags get cleared before exiting the link insert function, even if there is no actual selected node to insert.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk@61185 954f8c5b-7b00-dc11-b283-0030488c597c