[dfmc] Don't export or use *permissibly-ambiguous-generics*.
[dylan] Remove last traces of *permissibly-ambiguous-generics*.
Merge pull request #774 from waywardmonkeys/remove-permissibly-ambiguous-generics

Remove permissibly ambiguous generics
[dfmc-modeling] Fix ^known-disjoint? crash with singletons and unions.

We can't check ^known-disjoint? with the value of a singleton as this
may not be a type and ^known-disjoint? is defined on <type> and not
<object>.

This corrects an error made in commit 64c58256781aa34e1bdbe7c39ab9bdcf09148f28.
Merge pull request #775 from waywardmonkeys/fix-known-disjoint-for-singleton-union

[dfmc-modeling] Fix ^known-disjoint? crash with singletons and unions.
[dfmc] Remove remnants of flow-typist.

This removes code that was part of the flow-typist project which
was removed long ago.

This includes call-site-summary (css) and some alternative
typist entry points such as lookup-type and type-initializer-method.
[dfmc-testing] Revert "remove more unneeded files"

This reverts commit dccd85c08a164ea38e8630b0f025b845d11ec322.
[dfmc-testing] Remove unused / duplicate files.
[dfmc-testing] Switch from functional-dylan to common-dylan.
[dfmc-testing] Clean up whitespace.
[dfmc-testing] Remove unused manual-compiler-test macro.
[dfmc-testing] Don't use dfmc-execution.
[dfmc-testing] Make compiler back-ends available.
[dfmc-testing] Improve formatting.
[projects] Set platform name correctly on string-template projects.
[dfmc-testing] Minor renamings.
[dfmc-testing] Bring in testworks, but don't convert to it yet.
[dfmc-testing] Don't export anything.
[dfmc-testing] Switch typist-algebra tests to testworks.
Merge pull request #776 from waywardmonkeys/cleanup-flow-typist-remnants

[dfmc] Remove remnants of flow-typist.
Proofread looks good.