added list indexing and expressions as a separate branch.

ARR#0 and ARR#i#j works, but so too does
ARR#i.
ARR[i].
ARR[i+3].
ARR[i][j].
ARR[0].
Merge branch 'list-index-with-brackets-expressions' of https://github.com/Dunbaratu/KOS-1 into Dunbaratu-list-index-with-brackets-expressions