Bump version for 2.1.0 release

prepare for v2 release

Merge pull request naudio#584 from goddogthedoggod/fix-AdjustedPosition

Fixed 3 issues around AudioClockClient.AdjustedPosition

retiring Win 8 project

v1.8.3 release

v1.8.2 release

release 1.8.1

updating 1.8.0 release notes

simplifying creation of NAudio source code zip

updating versions for NAudio 1.7 release