Renamed the changelog classes and used UTF-8

- `DimensionsChangeSet` renamed to `DimensionsChangeLogEntry`
- `DimensionsChangeSetList` renamed to `DimensionsChangeLogSet`
- Made the `DimensionsLogParser` and `DimensionsChangeLogWriter` use a
defined UTF-8 encoding (falling back to undefined / platform default
encoding if that fails when parsing)
- Added 2014 to copyright years in source file headers, cleaned up other
header comments into class-level Javadoc
- Reordered imports
- Removed strange use of `StringCharacterIterator` in
`DimensionsChangeLogWriter`, and escape URL using XML, not HTML,
encoding