don't print empty stacktrace or vardump
add LICENSE
add REPL mode
show newline for ^C in repl
handle errors in repl
Merge pull request #2 from dbieber/master

Fix randInt
fix randInt for single inputs
improve ParseError
fix assigning to empty named list
allow assignment beyond the end of a list
default values for string and number vars
extend THETA
force labels to string
simplify expression reduction
allow randInt(high, low)