Reduce output and provide optional sections

[xkubov]

Currently, decompilation generates (apart from C of the current function) some other output - header, includes, comments describing content, additional comments at the end, etc.:

There are parts of the output that are not needed (header and meta-info could be displayed in other ways) and some redundant parts (number of detected functions and perhaps function prototypes in small output, ...).

Some other parts should be let on a user to define if they want to see them (headers, prototypes sections, comments with names of the sections, ...).

We should reduce not needed and redundant output and provide an option to minimize decompilation content - by setting evaluable vars in Radare2 (e?).