Release-0.7.6

This is another bugfix/upkeep release that, again, addresses problems with signals and client-side event arrangements.

• #796 partially fixes a concurrency problem with NotifyWhenAutowired under teardown
• #771 fixes a problem that can arise when the same type is injected from multiple threads at the same time
• #772 and #803 fixe a long-standing CMake installer inconsistencies
• #773 allows signal handlers to be mutable
• #775 removes the deprecated AutoInjectable type
• #777 makes invocation of CoreContext::Create on a stopped context harmless by changing the exception type to dispatch_aborted_exception
• #782 fixes an issue with autowiring::parallel and void dispatchers and #783 adds a barrier concept
• #774, #794, #812, #813, #814, and #815 makes signal behavior, especially under concurrent modification, much more predictable
• #786 implements SetThreadPriority on non-Windows platforms
• #780 implements a strong NotifyWhenAutowired sequentiality guarantee
• #785, #788, #779, #778 fix miscellaneous typos and comments throughout the codebase