Merge pull request #6 from RaMMicHaeL/pr_relay_restore_ip

Restore IP register from relay function to target function
Modifications to facilitate supporting multiple hooks for a single function:

* Use a relay function for 32-bit too, while a userData variable is just above it.
* Build the trampoline function in EnableHookLL, instead of MH_CreateHook.
* Break into a debugger (for now) when disabling our hook if another hook was placed on top of ours.
Implemented hooking a single function from different MinHook instances.
Use a mutex instead of a spin lock.

Pros:
* Works for multiple instances of MinHook.
Cons:
* Performance.
* MH_Initialize and MH_Uninitialize are not thread safe anymore.
Updated README