! Fixed: EXIF DateTime would not be changed if "Set to DateTimeOriginal" action is selected
! Readme, form captions: terminology adjusted to EXIF tag naming
+ Added checkbox "Leave unchanged" for cases when you just want to change DateTime field and/or last modified property. Option is saved in the registry
+ README.md: added some theory, small fixes
- Removed on-the-fly enabling/disabling of "Process" action, all the checks are inside ProcessFiles proc
! Improved behavior in case when some of EXIF tags are empty