Adding mw.smw.subobject to available smw functions

[oetterer]

Here comes the smw parser function "subobject" to the available lua functions.

I'm not sure, if I should have branched before my previous PR, since this now includes both. Sry for the mess...

Nevertheless. Againg, the implementation re-uses as much code as possible from the smw parser function call. It utilizes class ParserFunctionFactory to get the same kind of object, the normal parser function call to #subobject would use. It then defers parameter processing and the semantic storage process to this object the same way a normal parser function call would use.

Difference to the parser function call is:

• it does a preliminary argument processing to catch multiple input formats and some lua specific peculiarities
• it aborts on empty parameters
• it returns true on success and an array containing the error message in case of failure/warnings

[oetterer]

there is a copy/paste error in 1432e51. Shoud read Adding mw.smw.subobject to available smw functions

[oetterer]

I recommend closing this. after the two other PRs are in a satisfiable state and integrated in master, I re-add this. multiple PRs better not be done in parallel branches me thinks... :(

[mwjames]

Do you want to close this one?