Working on routine parsing
Working on routine parsing
Implemented the Routine class and routine name parsing in parser.cpp/.hpp
Added differentiate in routines.cpp
Added differentiate to routines.cpp
Implemented the unary minus and added continue; after each operator evaluation in eval_rpn
Improved formatting and added errors.h
Added support for scientific notation and fixed a bug about about skipping space in get_token
Added showrpn keyword to show rpn of expressions and that of stored functions
Returns NAN for divide by zero error and factorial of negative number.
Merge pull request #4 from sandesh-kalantre/sandesh

Sandesh:merged into master from sandesh.