Fix for #56: UTF8 encoder is broken

Man, all that for a single forgotten bit ;)
Simpler test for #56
Added test for #46: Path.add() does not make Uri absolute automatically
fixed a behavior problem with plusYears()
few more tests
build: run doc with no mtime check
Merge pull request #73 from DiegoCoronel/date_periodfrom_tests

Few more date periodFrom and periodTo tests
Fix for #44: Writer interface doc should specify that close() causes flush()
Changes relating to language module change Array.setItem() -> Array.set() (ceylon/ceylon.language#205)
Issue #74: Print whether the test passed or failed, plus the stacktrace when a test failed
Add group() to ceylon.collection, (ceylon/ceylon.language#193)
Add a test for group() in ceylon.collection, (ceylon/ceylon.language#193)
Remove accidental call to print()
Bitten by equals() :-(
Fix test failure exposed by #74, where we were using a LazyMaps which relied on capstured JDBC objects having an open connection. We returned the map but closed the connection in a finally block. Adds dependency on ceylon.collection, since I needed a Map implementation that wasn't LazyMap.
minor
collection: removed methods whose supertype implementation was enough
collections: they can now implement equals
HashSet: refine return types of union/intersection and friends
LinkedList: implement missing methods