Format tokens.l

Corrected some intendation, for making a straight line.
Also added some more whitespace for better readability
Clean main.cpp

Removed an obsolete "std::" statement, because there's a "using namespace std;" in Line 5.
Merge pull request #19 from Columbus240/patch-1

Format tokens.l
Merge pull request #20 from Columbus240/patch-1

Clean main.cpp