Updated changelog, better parsing and testing

* local-time/ChangeLog
	- Added entries for latest changes

* local-time/local-time.lisp
    - updated copyright date
    - decode-local-time now handles 2001-03-01 correctly
    - parse-timestring now partially honors JUNK-ALLOWED keyword
    - construct-timestring now always prints at least 4 digits for year
    - construct-timestring now puts negative sign in proper location
    
* local-time/local-time-test.lisp
    - deftest now has many more features
    - added encode-local-time test
    - added two more decode-local-time tests