LT-15173: fix crash exporting XHTML

Set default values for Digraphs and MapChars separately

Change-Id: Iddd3adad08bed773393272333c944d5c76a0d230
Handle HKLM access problems

 * If a Windows machine is broken and has trouble accessing HKLM,
   don't crash.
 * When possible, provide default values so hopefully it will
   work anyway.
 * See LT-15158.

Change-Id: I31aa410523768eb6147d9154aa79feebb70eec90
LT-15123: Make S/R 1st time Dlg easier to localize

Minimize line breaks, add instructional comment.

Change-Id: Ib87a7b9245839dac0fe752f46c6634bbbdd0a3d9
Fix LT-15181 (crash in FixFwData)

* If two custom fields with the same name are on different types
  e.g. LexEntry and LexSense it should not crash when testing the
  file after a merge.
* Modified some existing test data to prove the fix.

Change-Id: I9e02ae27a96ac32b8ed6b7738ba1633e151e1483