Reformat the project

- Next merge the upcoming docopt 0.7.0
Remove tests folder
Update to the latest docopt (the upcoming v0.7.0)
Complete the merging process of the upcoming docopt 0.7.0

- Remove unused object from the C code template
Suppress several warnings when compiling with C++ compiler

All suppressed warnings were about "deprecated conversion from string constant to ‘char*’". So far, I don't know how we should solve this for the default option arguments. The way how those are set atm. rise this warning.
Use <cstdio> etc. for C++
Suppress the rest of the warnings "deprecated conversion from string constant"

However, I'm not satisfied with the implementation so far... but it seems to work now. This solution also fixes the possible memory leak concerning a situation where user defines a value over the default value. The previous solution, although being much more elegant, whould have lost the pointer to the set default C string.
Fix the previous commit with better implementation

Literal strings are static automatically. See for example, http://stackoverflow.com/questions/349025/is-a-string-literal-in-c-created-in-static-memory
Rename docopt_c.py
Rename TokenStream to Tokens

This normalizes some vocabulary with the upcoming docopt.py 0.7.0. Additionally I decided to use pointers to the created Tokens record instead of copying it at every function call. In C this clearly indicates that we are in intend to change the values in the record.
Update docopt.py to the current master
Update usage-section conventions in example.docopt

- Also remove the redundant usage of DocoptExit in docopt.c.py
Rename docopt.c.py back to docopt_c.py. Closes #5.
Update README to correspond with the previous commit