Problem: Warnings from MinGW compiler. (John Marriott) Json test fails when
building without +float feature.
Solution: Init variables. Fix Json parsing. Skip a few tests that require
the +float feature.
Problem: Reallocating the list of scripts is inefficient.
Solution: Instead of using a growarray of scriptitem_T, store pointers and
allocate each scriptitem_T separately. Also avoids that the
growarray pointers change when sourcing a new script.
