crash with RMS and Latium map

[fabio]

Selecting Random map, Latium map and 3 players make the game crash:

ERROR: JavaScript error: maps/random/rmgen/tileclass.js line 83
TypeError: this.rangeCount[y] is undefined
  (139,289)@maps/random/rmgen/tileclass.js:83
  addToClass(139,289,6)@maps/random/rmgen/library.js:337
  @maps/random/latium.js:114
ERROR: Failed to load RMS 'maps/random/latium.js'
TIMER| GenerateMap: 73.5917 ms
ERROR: Map generation failed: RMS returned undefined
main.cpp(206): Function call failed: return value was -1 (Function failed (no details available))
Function call failed: return value was -1 (Function failed (no details available))
Location: main.cpp:206 (ProgressiveLoad)

Call stack:

(0x82ae2e2) ./pyrogenesis() [0x82ae2e2]
(0x827ab98) ./pyrogenesis() [0x827ab98]
(0x827bb53) ./pyrogenesis() [0x827bb53]
(0x827be3e) ./pyrogenesis() [0x827be3e]
(0x80558a0) ./pyrogenesis() [0x80558a0]
(0x8055e41) ./pyrogenesis() [0x8055e41]
(0x8056f9d) ./pyrogenesis() [0x8056f9d]
(0xb6d59ce7) /lib/libc.so.6(__libc_start_main+0xe7) [0xb6d59ce7]
(0x80556d1) ./pyrogenesis() [0x80556d1]

errno = 0 (?)
OS error = ?

[ben]

(In [9113]) Fixes rounding error on Latium map, would break with odd number of players. Fixes #761.