tests: New test-suite-only command __cmd

Adding or removing a command to/from a test has unfortunate effects:

* Before the previous commit: if the command consumes pseudorandom
  numbers, all subsequent users of pseudorandom numbers get different
  ones.  This has always been a major headache.

* Since the previous commit: all subsequent users of pseudorandom
  numbers get different ones whether the command consumes any or not.
  That's even worse.

* If the command uses BTUs, subsequent prompts are changed.  Not
  nearly as bad as the above, but still annoying.

Create a new command __cmd to allow compensating for adding/removing
commands for tests.  Throw in the ability to compensate treasury
changes for good measure.  Three arguments: command count, BTU use,
money use.

Usage example: say you add a convert command to a test, and it uses 3
BTUs and $15.  Then you compensate by adding "__cmd added 1 3 15"
right after it.

The command must not be available unless running_test_suite is on, of
course.  Make it require the new player command capability TESTING,
and give that to all players when running_test_suite is on.

The command is intentionally not documented in info.  Switch
running_test_suite off for info-test, to hide it (and any future
TESTING commands) from info-test.

Suppress the command counter increment for TESTING commands, so they
can be used without upsetting pseudorandom numbers

Signed-off-by: Markus Armbruster <armbru@pond.sub.org>

include/testing.h

@@ -0,0 +1,41 @@
+/*
+ *  Empire - A multi-player, client/server Internet based war game.
+ *  Copyright (C) 1986-2014, Dave Pare, Jeff Bailey, Thomas Ruschak,
+ *                Ken Stevens, Steve McClure, Markus Armbruster
+ *
+ *  Empire is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *  ---
+ *
+ *  See files README, COPYING and CREDITS in the root of the source
+ *  tree for related information and legal notices.  It is expected
+ *  that future projects/authors will amend these files as needed.
+ *
+ *  ---
+ *
+ *  testing.h: Test suite support
+ *
+ *  Known contributors to this file:
+ *     Markus Armbruster, 2014
+ */
+
+#ifndef TESTING_H
+#define TESTING_H
+
+extern int test_suite_prng_seed;
+
+/* Commands for test suite use */
+int testing_cmd(void);
+
+#endif