It doesn't matter to me if one is using FALSE/TRUE instead of 1/0
but I prefer a type (alias) which emphasizes boolean vars to int.
I changed 1/0 to FALSE/TRUE anyway.
- reduce compile time by a little bit (full-core: ~0.7s for me)
- thanks to 'include-what-you-use' for some help
- include Standard C header files before any other (coding style)
currently there are two scnenario to call mrb_run(), the first is
calling a proc, in this case mrb should create a new environment,
discarding all the variables except args, reciever and block.
the second is calling the newly generated irep, like in mirb.
in this case, the variables should be kept after mrb_run().
so we introduce mrb_context_run() to handle this seperately.