This is consistent with how the records in base work and avoids
misleading error messages at startup time when CA input links
have not yet connected.

Also added new fields IAOM and IAOV to facilitate this.

Also convert cvtRecord.html to cvtRecord.rst, and
integrate the csm doxygen generated API docs.

This version of hgen.pl will be used only if no other is available in the user's PATH

This was needed for better portability.

File-specific comments:

./csmApp/Doxyfile.external:
  Converted to the new doxyfile format
  
./csmApp/Doxyfile.internal:
  Converted to the new doxyfile format

  + bugfix with respect to the on-hold function: The "last" field
    of the csm_Function structure has to exist for each type of
    function that can be applied to the structure, one for
    csm_x(), one for csm_y(), one for csm_z(), for csm_dx() and
    csm_dy(). With only one field, it may happen for example,
    that when "on_hold" is used, csm_x() returns the last returned
    value of csm_y().
  + bugfix with respect to multithreading use:
    the semaphore used in functions like csm_x(), csm_y() and so
    on was given just before a return-statement which did a read-access
    on the function structure. This lead to a race condition where
    it was possible that one call of csm_x() returned the value of
    another call of csm_x() which was called by another task. Together
    with "last" field bug mentioned above, csm_x() could even return
    the value of the last csm_y() call, which is fatal...