Dedupe some utility code

[sandersn]

1. convertToArray is a duplicate of arrayFrom
2. inferFromParameterTypes delegates immediately to inferFromTypes
3. One usage of arrayFrom instantiated a whole iterator only to take the
   first element, which is the same as calling next.

[sandersn]

Note that I considered getting rid of arrayFrom in favour of iteration-based map/filter utilities, but the places that it's used don't look performance sensitive. They either run once per compilation (command line parsing, etc), during interactive use (getAllPossiblePropertiesOfType), or during error reporting (spelling suggestions)