Release-0.7.8

This release addresses some pessimisations in v0.7.7 and addresses certain usability concerns.

• #843 removes some finder modules that nobody needs and we no longer use
• #846 adds a TryDispatchEvent concept to DispatchQueue
• #847 makes autowiring::parallel's behavior a bit easier to understand
• #848 removes thread pools from CoreContext--this feature was unused and complicated the design