Made push_type_int{,_backwards}() static.

Introduced push_int_type() and push_object_type{,_backwards}().

Rev: src/builtin_functions.c:1.344
Rev: src/encode.c:1.82
Rev: src/language.yacc:1.225
Rev: src/operators.c:1.125
Rev: src/pike_types.c:1.148
Rev: src/pike_types.h:1.49
Rev: src/svalue.c:1.94