fix(opensmt/parsers/smt2/smt2lexer.ll): support dos-style newline

close #16.
fix(opensmt/parsers/smt2/smt2lexer.ll): add support unary minus '~'

close #17.
fix(util/scoped_env): fix output format
fix(tools/proofchecker/checker/lexer.mll): fix FNUM regex
chore(AUTHORS): remove whitespace
chore(travis): update DREALREPO secure key to point dreal/dreal