Config generator should have template string

[kryczkal]

In config generator - currently the generation logic for .h, .hpp is dispersed and created using echo

shoulde be something like

template = """
#ifndef example
#define example

{DEFINES_TAG}

{CONTEXPR_TAG}

#endif
"""

and then the tags be substituted with the generated stuff
etc, so that you know exactly what the end file will look like