Modori reference records

[craigsapp]

Related to issue https://github.com/humdrum-tools/verovio-humdrum-viewer/issues/664 and #663, allow for reference records to be switched between original and modern scores. This will primarily affect !!!OMD which is often used to display the movement designation such as Allegro at the start of the movement.

Encoding Allo. as the original version:

!!!OMD: Allo.
!!!OMD-mod: Allegro

Then modori -m will do this:

!!!OMD-ori: Allo.
!!!OMD: Allegro

Probably allow for any reference record type.

[craigsapp]

Implemented with commit https://github.com/craigsapp/humlib/commit/e470b65cf961145781a84f49a009df6feacb9ba0

Example:

!!!OMD: Allo.
!!!OMD-mod: Allegro
**kern  **text  **mod-text
*clefG2 *   *
*mclefF4    *   *
*M4/4   *   *
!!LO:TX:a:t=dip3:mod=mod3
1c  dip1    mod1
!LO:TX:a:t=dip4:mod=mod4    !   !
1c  dip2    mod2
=   =   =
*-  *-  *-

After running modori -m:

!!!OMD-ori: Allo.
!!!OMD: Allegro
**kern  **ori-text  **text
*oclefG2    *   *
*clefF4 *   *
*M4/4   *   *
!!LO:TX:a:ori=dip3:t=mod3
1c  dip1    mod1
!LO:TX:a:ori=dip4:t=mod4    !   !
1c  dip2    mod2
=   =   =
*-  *-  *-