Don't complain if the value already does not exist.

Make sure it does not modify the value if the data is invalid.

regedit: If the data for a given value is in an unknown format, then print an error and don't modify the value.

Note that '"foo"=' is not valid.

regedit: Remove cruft and make functions static, reordering where necessary to avoid forward declarations.

Remove the command parameter of processRegLines() as it can only be used with processRegEntry().