BUG: Handling end-of-file encountered in parsing numerical data in game files

[bcollin3]

If you call Game.parse_game() on a string that ends in a decimal utility value then the program will crash after a minute or two after consuming all of the system's ram.
For example:

import pygambit as gbt
s='NFG 1 R "prisoners dilemma"\n {"Player 1" "Player 2"} {2 2}\n -6 -6 -10 0 0 -10 -1 -1.0'
gbt.Game.parse_game(s)

will cause a crash but

import pygambit as gbt
s='NFG 1 R "prisoners dilemma"\n {"Player 1" "Player 2"} {2 2}\n -6 -6 -10 0 0 -10 -1 -1.0\n'
gbt.Game.parse_game(s)

will not.

[tturocy]

In GameParserState::GetNextToken() checks for the validity of the file after an attempted .get() are not done consistently, in particular in some places in which numerical data are parsed. This results in an infinite loop.