Minor fixups

Hi,
I fixed three minor issues that were affecting, IMO, the processing template library:

- I've updated .gitignore to also ignore folders bin and tmp; while it is likely each developer has her own .gitignore file, I believe it is better if the template takes care of hiding those folders created during the build process, like you already do with 'distribution'.

- when importing the project in Eclipse, the IDE will flag an error on the whole project. That is caused by a reference to the 'processing-core' codebase that exists in the classpath file. I deleted this reference as not required and confusing when doing the first import: I initially thought Eclipse wasn't seeing the core.jar and similar libs I had added to the project.

- I fixed issue #4 reported on GitHub. You were using the tag @example while describing its usage. This triggered the doclet to search for a file whose name was the explanation text itself (have a look at the error message reported in the ticket). 

All in all, very little stuff.
Thank you for your attention,

Best,
nico