discover gtest using ctest

[marvelous]

But tests fail at the moment:

[ RUN      ] WorldStateTest.WorldStateTestGroundAndElement
/var/home/marv/@/3-projects/33-scene/3310-darwin/Test/Server/world_state_test.cpp:117: Failure
The difference between height and 10.1 is 27.316573867739415, which exceeds 0.01, where
height evaluates to 37.416573867739416,
10.1 evaluates to 10.1, and
0.01 evaluates to 0.01.

[  FAILED  ] WorldStateTest.WorldStateTestGroundAndElement (43 ms)
[ RUN      ] WorldStateTest.WorldStateTestGroundAndCharacter
/var/home/marv/@/3-projects/33-scene/3310-darwin/Test/Server/world_state_test.cpp:156: Failure
The difference between height and 11.0 is 30.484937025383083, which exceeds 0.01, where
height evaluates to 41.484937025383083,
11.0 evaluates to 11, and
0.01 evaluates to 0.01.

[  FAILED  ] WorldStateTest.WorldStateTestGroundAndCharacter (35 ms)
[ RUN      ] WorldStateFileTest.LoadAndSaveFromLocalProto
/var/home/marv/@/3-projects/33-scene/3310-darwin/Test/Server/world_state_file_test.cpp:65: Failure
Expected equality of these values:
  world_state_
    Which is: 496-byte object <00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 33-30 38-33 2C-20 77-68 00-00 00-00 65-78 63-65 F0-57 6C-55 30-56 00-00 ... 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 20-E8 6C-55 30-56 00-00 20-E8 6C-55 30-56 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00>
  world_state
    Which is: 496-byte object <00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 00-00 A0-47 63-36 8C-7F 00-00 00-00 00-00 33-32 6D-00 00-00 00-00 00-00 00-00 ... 00-00 00-00 00-00 00-00 18-E8 6C-55 30-56 00-00 00-00 00-00 FD-7F 00-00 00-00 00-00 00-00 00-00 60-48 FA-F0 FD-7F 00-00 60-48 FA-F0 FD-7F 00-00 00-00 00-00 00-00 00-00 00-00 00-00 30-56 00-00>

[  FAILED  ] WorldStateFileTest.LoadAndSaveFromLocalProto (3 ms)