Merge pull request #459 from abeaumont/master

Add missing classes to limited-collections-2 and limited-collection-3 tests.
Remove patchable-constant macro.
Cleanup whitespace.
Use 'define function'.

A lot of older code used 'define constant' with a method literal
as the code probably pre-dated support for 'define function'.
Use ignore() on unused values.
Fix spelling of propagate.
Cleanup whitespace.
[doc] Begin documenting method dispatch.
Fold handle-missed-dispatch-1 into handle-missed-dispatch.

The code being removed that was commented out has been commented
out since it was originally added in the late 1990s and the
functions that it calls don't actually exist anywhere.
[doc,hackers] Additional method dispatch detail.
[doc,hackers] Fix indentation in build sys docs.
[doc,hackers] Fix link to jam-mode for emacs.
[doc,hackers] Improve formatting on Jam rules.
[doc,hackers] Document DylanLibraryJamIncludes.
[doc,hackers] Bump copyright date.
Remove remnants of tagged booleans.

Booleans don't get a tag bit anymore (values with a tag bits value
of 3 are now Unicode characters, not booleans).
Merge pull request #461 from waywardmonkeys/remove-boolean-tag-remnants

Remove remnants of tagged booleans.
[rt] Mark branch in profiling as unlikely.
Fix a couple of typos in comments.
Add note about new list of projects.