Xedit fixed errors, new gallery viewer and some minor changes

**Bug fixes:**
* Labels on Xedit when selecting elements,
* solving apply elements bug. Allowing 2 or more apply elements consecutives,
* a Smarty warning when creating a new empty node,
* some errors related with the new fonts added on Ximdex.

**Improvements:**
* New *image gallery* action for image folders.
* Avoiding MySQL queries with *asterisks* on them. We now specify all the fields to return.
* Allowing XSL files to be imported on Xedit. Without this rule, Xedit can't renderize any content.
* Visual mark for unsaved changes on *codemirror*.