Some modifications to help integrate externale html templates (i.e. form themeforest).

Add ability to change block tag instead of "DIV": in blocks editor a new field BlockName is used to substitute opening tag DIV (i.e. <section>, <article>,..).

A particular "split function" is used to split html blocks inside block content.

All modifications require a "new table field" in blocks table. New field is BlockName, type string, equal to to BlockID.
New field in blocks table
new icon for blocks editor, now admin icons have relative path instead absolute
graphic error in admin section corrected