Replace bind with a version that uses const references

[bremoran]

This version of bind does away with stdarg and uses a friend class instead. This allows FunctionPointer to work with all types of argument, including references.

[bremoran]

cc @bogdanm @niklas-arm @pan- @autopulated

[autopulated]

:thumbsup: looks much nicer, can't see anything obviously wrong – notice we still don't have tests checking the lifetime of argument objects though?

[bremoran]

Yes, we definitely need more extensive testing. I have written some more tests, but they don't go to that depth yet either.

[bogdanm]

I'll try to run the Event test on this change (and maybe automate the test a bit more in the process) since it touches some lifetime aspects, but if there's not enough confidence, it's safer to merge this after the TechCon release.

[bremoran]

Since github hides commit messages by default, here's the message from the previous commit:

• The previous code has a bug, which prevented minar from working. In bind, the FunctionPointer’s member caller, object, and member were never copied to the new FunctionPointerBind. This meant that no bound pointers would work. This is corrected by adding a copy constructor for initializing a FunctionPointerBind with a FunctionPointerBase.
• Added numerous tests to validate the new implementation. There are still too many copies of arguments. A single FunctionPointer call results in 3 new instances of each argument. This could be reduced with some additional work.
• Removed the indirection from operator() to call() since this introduces one additional copy of each argument.
• Added documentation about yotta config options.

[bremoran]

Bump for review

[bogdanm]

Looks good. Let's merge it and check if anything breaks.