Extend icon search path to get symbol list icons working when using a non-standard installation prefix.
Query default icon theme only once to improve startup speed.
Store the line number separately in the tree store.
Remove utils_get_local_tag().	       


git-svn-id: https://geany.svn.sourceforge.net/svnroot/geany/trunk@1731 ea778897-0a13-0410-b9d1-a72fbfd435f5