Upgraded dictionary source reference format.

Dictionary format change. (Upgraded 'VERSION' to 1.4.)

* Systematized all source references so that they now have 1:1
  correspondence to transcript files. Rewrote 'def:' and 'ref:' field
  content (as well as source references given in the 'desc:', 'com:' and
  'cite:' fields) to this new format. -- This means there was a HUGE number
  of changes in the dictionary (source references for *all* words).

* Removed old (now pointlessly redundant) 'file:' field.

* Upgraded dictionary check tools (`check-dict`) and dictionary web search
  have to work with the new source reference format. (Web search now
  present each source reference as a link to the corresponding transcript,
  instead of having a separate field for that).

* Many minor changes and improvements to the dictionary.