Changelog for xstacks.fs, xstacks-defwords.fs, xstacks-test.fs, and
twx.fs.

This the ANS Forth version of xstacks.

Unattributed changes are by David N. Williams.  Last revision dates in
source files may reflect cosmetic changes not recorded here.  Unless
otherwise stated, tests or benchmarks mentioned here have been run under
MacOS X.

Version 0.7.0
21Aug21 * Split xstacks.fs into xstacks.fs and xstacks-defwords.fs.
	  Removed the PFE kludge and XSTACK-DEFINING-WORDS switches. 
	* Bumped xstacks-test.fs from 0.6.5 to 0.7.0.  Replaced PFE
	  switch by USE-PFE-XSTACKS.

Version 0.6.6
25Oct09 * renamed FIELD: as +FIELD.

Version 0.6.5
20Sep06 * Added a switch in xstacks.fs to turn on the pfe implementation
	  of the basic xstack words, with off as default.  Intended
	  exclusively for testing the pfe implementation of the basic
	  words via their use in the xstacks.fs version of the defining
	  words.  Added a PFE switch to xstacks-test.fs, for that
	  purpose.  When the defining words are wanted with pfe,
	  xstacks-pfe.fs is better.
	* Added double-cell basic and defining words to xstacks.fs;
	  xstacks-test.fs worked with pfe and gforth.  Also worked with
	  pfe versions of the basic words.

Version 0.6.4
17Sep04 * Assigned original file name, xstacks.fs, to future ANS Forth
	  version, for which this is to be the change log.
 6Sep06 * Renamed test-xstacks.fs as xstacks-test.fs.
 9Sep06 * Removed loading xstacks.fs from twx.fs.
19Dec06 * Added basic xstack words and recoded defining words for single
	  cell operations.
	* Made double cell tests in xstacks-test.fs uncommentable. 
	  Tests revealed minor errors.  The uncommentable,
	  nondestructive underflow tests don't abort, because we didn't
	  code those exceptions.
20Dec06	* Bumped version number to agree with xstacks-ext.c.
  
Version 0.6.3
21Sep02 * Added DROP after xstack structure to remove lingering offset
	  due to no /STRUCT: definition.
17Sep04 * Started new file xstacks-pfe.fs.  Rebuilt pfe execution and
	  xstacks modules with pfe-0.33.34 and verified that
	  test-xstacks still works.

Version 0.6.2
16Sep02 * Replaced qdstruct.fs with plainstruct.fs
        * Changed colon prefix for defining words to colon suffix.
17Sep02 * Removed indirect break field from xstack structure and updated
	  xstacks-ext.c.
        * Made xstacks-ext.c into a 0.32.xx pfe module.
        * Updated test-xstacks.fs and ran all tests successfully.

Version 0.6.1
22Feb01 * Start pfe port.
26Feb01 * Last change.

M680x0 ^Forth Version (stack.fs)
 2Dec95 * Start.
22Sep96 * Last change.