overhaul events subsystem: API changes, ghashtable split for reg/mem events, signal handler in example and various bugfixes and improvements
Merge pull request #56 from Zentific/events

Update Xen Events
Events : add MSR write monitoring capability
Events : Initialize events in VMI_INIT_PARTIAL mode (so MSR, CR0, CR4 can be observed in addition to memory page events without needing to wait for the conditions necessary for VMI_INIT_COMPLETE)
Events : add some notes on MSR writes observed for a few OS versions and their values.
Events : ensure that LibVMI is in a sane state before event setup for full init.
Merge pull request #58 from smaresca/msr_events

Events: add MSR write monitoring for Xen
Initial commit of single step functionality for xen mem_events

created a single_step event processor and fixed some oversights

added some error handling

created a single-step event example

Refactoring for enabling multiple vcpus on single step

renamed some single step macros and exposed a function to stop single stepping on a single vcpu
temp fix