Remove no longer useful options;
* chain (sorry, supporting the btc chain just doesn't seem worth it)
* initiatecashconnections, we only allow Cash connections now.
* flexiblehandshake, same for incoming. Reject non-cash ones.
The compact-message-format has numberic limits that were not
being managed well.
This unit test makes sure we keep the limits at;
Negative number is 0x7FFFFFFF (aka INT_MIN)
Positive number max is 0xFFFFFFFFFFFFFFFF (aka ULONG_LONG_MAX)
The inconsistent limits is because the API. We use ints for negative
numbers and unsigned-longs for larger numbers.
This keeps the API simpler for the common cases.
Get rid of the weird boost signals setup
Move it to a new library 'interfaces' which is
for stuff that has no dependencies and can avoid
creating inter-library or cicular dependencies.