mutiple x64 warnings about loss of data under VS2013

[gabime]

format.cc(636): warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data
format.cc(642): warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data
format.cc(656): warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data
format.cc(661): warning C4267: 'argument' : conversion from 'size_t' to 'int', possible loss of data

[vitaut]

Fixed in c3ba615. Thanks!