rename PROTOBUF_C_FIELD_FLAGS_PACKED to PROTOBUF_C_FIELD_FLAG_PACKED.
rename ProtobufCFieldFlagType to ProtobufCFieldFlag.
wrap some particular long lines.
update documentation.
for clarity, use a "uint32_t" instead of "unsigned" for the 'flags'
field in _ProtobufCFieldDescriptor.
per https://code.google.com/p/protobuf/source/detail?r=50, the license
on google-originated protobuf code was switched from Apache-2.0 to
BSD-3-Clause (so-called "New BSD" license). update any of the google
license statements to use this new license.
per email with dave, drop the third clause on his BSD-3-Clause license,
so this now becomes BSD-2-Clause.
make sure to use consistent indentation and wrapping throughout.
