regexpr: sync'ed changes from Lazarus synedit component directory
regexpr: sync'ed changes from Lazarus synedit component directory

- fixes the spelling of 'useful'
- Many 64-bit support fixes. Mainly Integer vs PtrInt changes
- Correct implementation of TRegExpr.GetMatch()
- extra debugging measures

wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI,wkitty42/fpGUI