support reading a field name rather than a field tag.

support reading a field name rather than a field tag.

Refactored 'speed' generated write of arrays to call Write???Array.  This may
have impacted speed write speeds for arrays of non-reference types due to the
use of non-generic IEnumerable and the subsequent boxing of value types.  This
could be addressed later if desired.

Slight refactoring of Extensions to support lookup by name, added compatibility tests for text and binary formats.

Use that within the build for the address book sample.

- Defaulted service_generator_type to NONE
- Added /protos/extest/unittest_generic_services.proto to test services
- Migrated unit tests to use the new generic services for testing

One-off patch to convert Unix line endings to Windows ones for generated source. Currently not sure why they ended up as Unix line endings after Git to Mercurial conversion, but we may need to tweak some repository settings.