Remove RiteFile as no used.
Reduce temporary memory allocations. They are redundant.
Modify the type of line-number to uint16_t. Type short is not portable. And it cannot be more than UINT16_MAX because of the mrbc binary format.
Reduce temporary memory allocations. They are redundant.
Remove str_to_mrb_int(). There is some reasons.
 It is not used in the core.
 It does not have mrb_ prefix.
 strtol() is slightly heavy and we have similar API.
Add CHAR_BIT check. There are uint8_t to char conversions.
Merge pull request #1104 from monaka/pr-simplify-dump-load

Simplify dump/load