Coverity fix with vmi_get_bit

CID 703173 (#1 of 1): Unintentional integer overflow (OVERFLOW_BEFORE_WIDEN)overflow_before_widen: Potentially overflowing expression 1 << bit with type int (32 bits, signed) is evaluated using 32-bit arithmetic, and then used in a context that expects an expression of type reg_t (64 bits, unsigned).
Merge pull request #208 from tklengyel/coverity_fixes9

Coverity fix with vmi_get_bit
Fix cache interface mismatch
Fix for step_event with callback resetting
Merge pull request #209 from tklengyel/step_fix

Fix for step_event with callback resetting
Merge pull request #210 from tklengyel/cache_fix

Fix cache interface mismatch
Fix step event with callback
Merge pull request #211 from tklengyel/step_fix2

Fix step event with callback
Generic cleanup of the Xen driver code
Fixing some VMI_DEBUG warnings.
Fix building LibVMI with xen-events on old Xen libraries and add static conversion matrix for flags
Merge pull request #212 from tklengyel/xen_driver_cleanup

Generic cleanup of the Xen driver code
Merge pull request #215 from awsaba/debug_warnings

Fixing some VMI_DEBUG compiler warnings.
Merge pull request #213 from tklengyel/event_fix

Fix building LibVMI with xen-events on old Xen libraries and add static ...
Add empty xen_are_events_pending function when events are disabled
Merge pull request #216 from tklengyel/pending_events_fix

Add empty xen_are_events_pending function when events are disabled
Merge branch 'master' of https://github.com/bdpayne/libvmi into staging