AbstractBuildForm.php: change 'annotate' and 'imageCut' to use SIP encoded download.

HelperFormElement.php: AppendFormElementNameImageCut()
Support.php: Force Sanatize Class fuer FE.type=imageCut.
AbstractBuildForm.php: Add source filename to SIP
QuickFormQuery.php: Call $save->processAllImageCutFE();
Save.php: processAllImageCutFE(), extractImageDataReplaceFile()

DatabaseUpdateData.php: extend FormElement.type to 'imageCut'.
Support.php: extend joinPath() to join path parts optionally without using file as absolute path. Implement unit tests.
Download.php: doc
AbstractBuildForm.php: implement FE,typ=imageCut
formEditor.sql: update FE with new element imageCut.

#5133 / sendmail: subject and body html entity decode: Introduce options for 'subject' and 'body' to switch on/off HTML encoding / decoding

Html2Pdf.php: Add error codes and a hint on wkhtml fails.

SendMail.php: in error message show commandline.
test.html: remove

Patch for sendEmail (see https://unix.stackexchange.com/a/68952).

qfq-letter.css.less: redefined h1, letter-receiver

Store.php, AbstractBuildForm.php, QuickFormQuery.php, Save.php: change signature of appendToStore() to be eqal to setStore().
Unittests for appendToStore.php