libfoundation: Merge separate typeinfo enhancements into feature-typeinfo.

Pull-Request: #1539
Pull-Request: #1546
Pull-Request: #1565
[[feature-optionaltypes]] libfoundation: Finalize optional typecodes.
[[feature-propersetvalueref]] libfoundation: MCSetRef -> "livecode.lang.bitset".
[[feature-propersetvalueref]] libfoundation: Add MCProperSetTypeInfo.

Add a named alias of MCProperListTypeInfo and its optional variant.

Note that this is currently not hugely useful, because calling
MCValueGetTypeInfo() on an MCProperSetRef will return
kMCProperListTypeInfo.
Merge branch 'feature-typeinfo' into feature-stackarr.
Revert "[[feature-stackarr]] Add "object reference" type info."

This reverts commit 8cec9d284d82b9974fd9ab0aac861b70ba3ca6da.  It
looks like a more comprehensive solution will be required.
[[feature-stackarr]] MCImage: Add state record support.

This control type was missed out in initial audit of affected classes.
[[feature-stackarr]] Add MCObject::getpatternid() accessor.