* Add testcase
This tries to use a concept with a doc comment which currently leads to a segfault
* Ignore nil nodes which happen when there are doc comments in new style concept
This was done instead of semming the comments since `semConceptDecl` says it only supports lists of actual statements
* Go with alternative fix: Sem comments but ignore them
Since `nil` could mean anything it is best to not silently ignore it (In case another nil problem happens in future
Also fix test case so it isn't an infinite loop
* fixes#15210 [backport:1.2]
* make tests green
* make ordinal work
* makes Swapable test compile
* make Indexable example work
* concepts: 'self' is now 'Self'
* concepts: make Dictionary example compile
* document the new concept implementation
* concepts: make typeDesc work properly
* concepts: allow documentation comments (d'oh)
