Add Array.indexOf (sdgoij)
Add Array.lastIndexOf (sdgoij)
Fix Array.indexOf to be compliant with 15.4.4.14
Add toValue_* for more straightforward value conversion

(When the type being converted is obvious.)
Add Array.every (sdgoij)
Fix Uint32 Array/String indexing

Also, a bunch of toValue_* streamlining
And maybe a few miscellaneous tweaks
Array.concat does not require length be a Uint32
Change handling of undefined in .Export

This fixes #28