[TASK] Optimize FormEngineValidation, Part I

The implementation of FormEngineValidation has been improved at some parts:

- The parsed integer value in FormEngineValidation.formatValue is now
stored in a variable to prevent parsing the same value multiple times.

- The `nospace` evaluation has been improved: Instead of checking each
character, a regex is applied.

- The `ltrim` and `btrim` implementations are now regex based. There are
already native JavaScript implementations, but not supported by every
browser.

- parseInt does now really a parseInt() call and checks for NaN.

- The dirty state of the form is now stored in a variable after changing
a field, the DOM is not traversed after clicking "Close" anymore.

Resolves: #72485
Releases: master
Change-Id: I3f166e65a949138595c9828684ea6c15a0deefc7
Reviewed-on: https://review.typo3.org/45348


Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>