Initial commit
Scanner and parser base
Parsing base, symbols, domain
Parser, bugfixing, multi argument lambdas, currying support
ScannerBase: added keyword/identifier support; collected the ugly
charsets in constants
Rudimentary PrettyPrinter util (for showing let expressions nicely)
Refactored expression pretty printing
Added let-expressions (model + parsing)
Support parameters in definitions (they'll be curried later)
Close variables properly in Context