Suppress compiler warnings.
Delete REBDCL type definition (no longer used in code).
Based on mul64 since it updates reb-c.h
Get rid of INT_64_MODE (the code is not consistent with its opposite anyway)
Use C99 integer definitions where available
Use typedef long i32 for non-C99 and non LP64 compilers
Merge pull request #147 from ladislav/compiler-warnings

Suppress compiler warnings. Accepted, but with the comment posted to this change, that should anyone have a problem compiling Rebol core for some odd platform, that we find a fix.