FEAT: transferring PIC flag to target emitters.
FEAT: [IA-32] loading ebx with IP address at beginning of CODE segment.
FEAT: [IA-32] freeing EBX register for using it as IP-relative pointer.
FEAT: [IA-32] avoid duplicated code for floats value loading/storing in FPU registers.
FEAT: [IA-32] added PIC support to global variables.
FEAT: linker is now able to emit relative references to CODE and DATA segments.

All Red & Red/System tests are passing except runtime error test. It seems Red/System runtime handler is not called anymore by Windows (untested on other platforms).
FEAT: [IA-32] added ebx restoration in prologue for callbacks.
FEAT: [IA-32] Added PIC support to imported functions calls.
FEAT: PE file emitter upgraded to allow relative addressing for imported functions calls.
FEAT: [IA-32] added PIC support to function pointers.
FEAT: load pointer variables slots dynamically when in PIC mode (avoids absolute addresses added at link-time in DATA segment).
FIX: missing function context pointer restoration on EXIT/RETURN.
FIX: [IA-32] 'callback keyword support re-activated. Fixes some ebx corruptions on external calls.
FEAT: added relative addresses calculation to ELF's imported symbols.
FEAT: added proper function prolog to special ***_start entry-point (fixes ebx corruption on Linux).
FIX: [IA-32] wrong offset in Linux syscall.
FEAT: minor restructuring of the relocation offset calculation in ELF
FIX: issue #411 (Semi-random compile crash), new attempt at working around this Rebol internal heisenbug.
FEAT: [IA-32] replaced exit() call with proper function-like epilog to global code in order to return to __libc_start_main() parent call on Linux/Syllable.
FIX: regression on pointer storing in data segment for non-PIC mode.
FEAT: better handling of cases when a main() wrapper is needed around global code.

Now it is restricted to executables on Linux/Syllable only.
FIX: wrong option checking for generating main() wrapper.
FEAT: activated ASLR and DEP features for Windows Red binaries.
FIX: avoid generating callback prolog/epilog for function pointers called only locally (not by an external code).

Reduces Red binaries by ~1500 bytes.