Added emulator detection (#651)

* Added emulator detection

* Fixed missing assignments

* Disable interrupts around the count factor test

* Added more comments to emutest

* Changed PJ64 enum values so the versions work as a bitfield

* Updated README

* Fixed comments

* Updated enum values so you can safely AND and OR all emulator version flags together

* Remove redundant gIsConsole, gIsVC, and gCacheEmulated global variables

* Changed console check to be more future proof against Ares

* Use assembly file instead of casting to a function pointer

* Moved round_double_to_float back to its own compilation unit

* Moved the ParallelN64 check before the Ares check for better future-proofing

* Align pj64_get_count_factor_asm with cache lines... not that it actually matters for pj64

* Adjusted some comments

* Made emulator check thread-safe on emulators that emulate PI timings

* Added gIsConsole macro for backwards compatibility

* Added cen64 to INSTANT_INPUT_BLACKLIST

* Updated comment

sm64.ld

@@ -160,6 +160,7 @@ SECTIONS
 #ifdef EEP
       KEEP(BUILD_DIR/asm/vc_bin.o(.text*));
 #endif
+      KEEP(BUILD_DIR/asm/pj64_get_count_factor_asm.o(.text*));
       KEEP(BUILD_DIR/asm/round.o(.text*));
 
       BUILD_DIR/src/boot*.o(.text*);