Update warehouse interface tile to remove items with quantities in
excess of that specified in the interface filter list.  Closes #182
clean up block-icon lookup (should fix crash reported on forums)
implement addition of escape chars to empty quotation marks whenever
saving out a json value.  upon parsing, skip any quotation marks that
have been escaped.
Should resolve issues of parsing signs with " in their text.  Closes
#184
Merge branch 'master' into 2.4