functions for contracts types using the ABI json file as input (WIP)

- remove BTS P2P code which depended on fc threads which depended on
deprecated boost::context API

- remove fc submodule and making fc part of eos repository

Only one call, but that call works!

Define a new p2p_plugin as the adaptor between appbase and the old P2P
library, and wire things together. This is mostly working, but for some
reason peers won't stay connected to sync, but instead just drop their
connection (with a TCP reset, no less) right before syncing, without
bothering to log about why. I suspect the failure is at a lower level. :
(

The producer plugin (now called producer_plugin) is now adapted to the
new appbase system, and appears to be working correctly.

Also, eliminate some boilerplate around OBJECT_CTOR macro! Now you can
OBJECT_CTOR(objname, (field1)(field2)) to indicate that field1 and field2
are dynamically allocated objects and need to be initialized with the
allocator.

Bring in chain_plugin, net_plugin, http_plugin; wire appbase and plugins
into existing infrastructure, remove old app infrastructure.