BibEdit: refactoring and fixes
- Refactoring of functions related to editable area change
- Sets max characters on fields/subfields
- Avoids double bind of editable area. Was causing troubles.
- Fix bug in field tag modification undo
- Fix switch to write mode
- Fix merge with template. Record was not being ordered after merging with template, so operations on the recstruct where not being done correctly
- Change in css to always display scrollbar in webkit-based browsers.