BibEdit: multiple bugfixes

• fix message when deleting record

• fix split of subfields

• avoid auto-scroll when adding in position

• optimized for loops that were calculating length in every iteration

• removed unused parameters

• fix conversion of subjects

• clean xml chars before formatting preview

• fix apply field template

• fix when deleting some subfields from field template and saving the field.

• fix for chrome/safari to select text box content if it is volatile