vc build update
replace typedef'ed type uintmax_t by its long form unsigned long long

It seems this type is not yet available in MSVC9, only in later versions.
add and use constructor (instead of assignment)

This fixes a MSVC warning about "cannot instantiate
customcodecvt_do_conversion_writer".
make included boost headers more specific

This works around a compile problem in MSVC9.
(some conflict in those boost headers ?)