site: update home page text, fix issue with links from documentation chapters
docs: update non-documentation chapters
docs: update spray-caching chapters
docs: update spray-can chapters
docs: update spray-client chapters
util & http: cosmetic improvements
routing: (re)add the `unary_!` operator to PathMatchers
client: small clean-up
httpx: small clean-up
routing: rename ExceptionHandler.fromPF and RejectionHandler.fromPF to simple `apply`
testkit: small cleanup
routing: remove inconsistent default redirectionTypes on `redirect` directive & co, smaller clean-ups
sbt: change version to 1.1-SNAPSHOT
site: fix remaining problems in documentation link construction
docs: upgrade all chapters to latest state