Fix typos in jmappane doc
Update docs for mouse wheel example

Use geotools 12 API.
Update example to use MapPane#getWorldToScreenTransform

The old API has been removed? Observed in v12.
Link to GeoTools project on JIRA

Since GitHub issues aren't used, link users directly to the JIRA page for the project.
Merge pull request #601 from leif81/patch-4

Link to GeoTools project on JIRA
Merge pull request #593 from leif81/patch-3

Typo and API updates to jmappane doc