Continuous prerelease

the comma (#23)

It turns out that `;` cannot consistently be used for parameter lists
with defaults, so we revert back to using `,` to separate identdefs
except when doing so would result in AST inequality - this works for all
known cases and returns us to comma-land generally.

* fix missing `:` in command post-statements
* fix parsing of top-level statements with `;`
(https://github.com/nim-lang/Nim/pull/23088)
* fix doc-comment support after `=` for vars, consts etc