Bignum additions: a) small number function call emulation using Gmp, b) intp,...

Bignum additions: a) small number function call emulation using Gmp, b) intp, c) sprintf %O (describe_svalue), d) sqrt and e) casting from float to integer.

Rev: src/bignum.c:1.4
Rev: src/bignum.h:1.5
Rev: src/builtin_functions.c:1.188
Rev: src/modules/_math/math.c:1.23
Rev: src/opcodes.c:1.44
Rev: src/svalue.c:1.46