[M3commit] [modula3/cm3] 237d29: Comments and versioning of CM3 IR

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/modula3/cm3
  Commit: 237d29ba54df977c4e0f0e72de7d0ad656ab4213
      https://github.com/modula3/cm3/commit/237d29ba54df977c4e0f0e72de7d0ad656ab4213
  Author: Rodney Bates <rodney.m.bates at acm.org>
  Date:   2017-02-22 (Wed, 22 Feb 2017)

  Changed paths:
    M m3-sys/m3front/src/misc/CG.i3
    M m3-sys/m3middle/src/M3CG.i3
    M m3-sys/m3middle/src/M3CG_Ops.i3

  Log Message:
  -----------
  Comments and versioning of CM3 IR

Add type to denote versions of CM3's intermediate representation,
which has changed a number of time.  This is unused as of this
commit.

Also, many comments explaining the IR.