Fixed 2 small logging bugs
Added constant instructions:

Constant instructions are needed for code like factorials where
literals cannot be compiled away, since they are part of a compound node.

- Added constant instruction and the shorthand for creating it in the core init file
- Moved the destination functionality of operationInstruction and constant to a common superclass
- Changed read for the new instruction
- Made a general function that reads values from a statement.
- Made some naming changes to reflect this
- Updated documentation and language files to reflect this.