[PATCH 0 of 7] help: format help text using RST

[Olav Reinert]

This set of patches changes the help system so that all help text is formatted
using RST. The first patches contain some refactoring. Then a sequence of
patches follows which change the helper functions to use RST formatting
internally.

In the final step, the helper functions are changed to simply return the RST
text they produce, instead of printing it themselves. The main help function is
then changed to assemble the RST pieces and to format and print the entire help
text.