message: Fix for - db.revision() != headblocknum on start
  abort pending changes prior to shutdown
  pop undo state on startup in case we crashed without aborting pending
  warn user when we load in this state as other things may be wrong
diff: @@ -171,6 +171,11 @@ struct controller_impl {
  initialize_fork_db(); // set head to genesis state
  }
  + while( db.revision() > head->block_num ) {
  + wlog( "warning database revision greater than head block, undoing pending changes" );
  + db.undo();
  + }
  +
  FC_ASSERT( db.revision() == head->block_num, "fork database is inconsistent with shared memory",
  ("db",db.revision())("head",head->block_num) );
  @@ -1012,6 +1017,7 @@ controller::controller( const controller::config& cfg )
  }
  controller::~controller() {
  + my->abort_block();
  }
  