MpaDecFilter: missing "return S_OK;"
update Release.txt
update Little CMS to v2.5 (git d504603)
CONTRIBUTING.md: mention the precommit hook script
Readme.md: switch to Atx-style headers
Readme.md: minor improvements
Initialize variables in the constructor.
Cppcheck fixes:

* reduce variable scope
* remove unneeded variable assignments
Fix camelcase word "Charset".