removed trailing whitespace
improved dimension checking. need to propagate changes.
some minor changes to dimension. need to replace shape_str function
cleaned up the parser section. moved symbol table to lexer
polished up parser
trying to clean up old code and remove dependence on dimensions
added solve interface.
checkpoint. nothing works anymore.
almost done refactoring dimension code.
refactored dimension. made life easier for everyone.
modify a test script
refactored and lint'd
modified readme. renamed expr to coeff_expr.