[Truffle] Collapse literal Fixnum nodes.
[Truffle] Clarify that the nil node is a kind of literal node.
[Truffle] Collapse array literal nodes.
[Truffle] Give the hash literal a single array of children.
[Truffle] Expand the Hash literal node.
[Truffle] Remove short names for nodes.

We never seem to use them and they're redundant anyway.
[Truffle] Pull the JRuby Truffle options into RubyContext so they're more simply final.
[Truffle] Remove prefix on options when they're obviously in Truffle's scope.