Rewrote some doc. Extend sql commands to be recognized in QFQ vars (have been already subscribed in that way in Manual.rst).

Fixes #6914. Final implemention of customized typeMessageViolation. Incl. unit tests. New escape mode 'C' - escapes ':' by '\'.' - useful for variables in variable definition.

Refs #7743. Move error mesages to Constants.php. Unit tests use those constants now. 'data-pattern-error' only delivered if a 'pattern' is given. 'required' attribute only delivered is set.

Refs #7743. Detection of 'pattern error' on per QFQ default, custom instance wide, per form or per FormElement - per FormElement overwrites other. System specific generated overwrites QFQ static default, instance wide default. Move default pattern to constants.

Refs #7743. Add unit tests. Make default error text more specific (only if default error text is not explicit set in config, form or form-element)

F#7747: New options to import Excel files: importNamedSheetsOnly, importSetReadDataOnly, importListSheetNames

See merge request !120

Fixes: 7685. Open FormElement from QFQ error message and save modified record: error about missing {{formId:F}}

FormElement.type=select: fixed problem with dynamic update and mode=readonly - list was still selectable.

Fe label text align right

See merge request !119

Fixes #7620. Label align left/center/right. Defined by config/form/formelement. FormEditor slightly redesigned.