Added Annotation ProtoIgnore. This annotation can be used when creating runtime schemas using Tags, and wanting to ignore a field (without deprecating it). Wrote unit tests for creating schemas with fields annotated with ProtoIgnore.
Removed unused code in protostuff-runtime/src/test../DeprecatedFieldTest.java.
Renamed ProtoIgnore to Exclude and merged two if-cases.
Corrected typos.
Moved the check for the Exclude annotation to filter out these fields earlier (by the time transient and static fields are filtered out).
Merge pull request #21 from jelgh/master

Added annotation to be able to ignore fields when creating schema from @Tag