Add a macro `enumLen` which is used to determine the number of items in
an enumeration type to the `typetraits.nim` module. Also, add unit tests
for it in the `ttypetraits.nim` module.
Related to nimlang/Nim#15824
* typetraits: add support for nnkTypeOfExpr
* typetraits: don't wrap typedesc symbols in StaticParam
* typetraits: add nested generics support to genericParams
* typetraits: make genericParams understand array[I, T] whackiness
Also moved tests to ttypetraits
* typetraits: clarify comment on genericParams
* rename 'lenTuple' to 'tupleLen'
Rationale:
`lenTuple` is a tuple consisting of lengths (e.g. `(1, 5, 0)`),
`tupleLen` is a length of a tuple (e.g. `tupleLen((1, 5, 0) == 3`)
* rename 'lenVarargs' to 'varargsLen'
The same rationale as a previous commit. Consistency.
* fix deprecation; fix indentation
* git clone: use -q
* fix Warning: pragma before generic parameter list is deprecated; fix typo
* bugfix: sysTypeFromName("float64") was never cached
* remove disabled (and obsolete) ttypetraits; rename ttypetraits2 => ttypetraits
* D20200105T085828 fix super strange bug that causes CI to fail: builds.sr.ht with: `Error: Settle timed out after 120 attempts`