Eventually multisign will need to be enabled onto the network, at
which point compiling it in or out will no longer be an option.
In preparation, the compile guards are removed and multisign is
being enabled with a Feature.
You can locally enable a Feature using your config file. To
enable multisign with your config file add a section like this:
[features]
MultiSign
The exact spelling and capitalization of both "features" and
"MultiSign" is important. If you don't get those right multisign
will not be enabled.
There is a minor issue. The "sign_for" and "submit_multisigned"
RPC commands are only enabled if multisign is enabled. However
those commands are still shown in the help message even if
multisign is disabled. This is because the code that produces
the help message doesn't read the config file (where the Features
are kept). This problem will become irrelevant once multisign is
enabled onto the network.