…, it's pretty slow right now.

Cache a reference to Encoding.UTF8 - the property access is (rather surprisingly) significant.
Additionally, when we detect that the string is all ASCII (due to the computed length in bytes being the length in characters), we can perform the encoding very efficiently ourselves.

… a single byte.

Aside from anything else, this will be used for all tags for fields 1-15.

This makes repeated fields really awkward at the moment - but when we reimplement RepeatedField<T> to be backed by an array, we can cast the array directly...

Remove ICodedInputStream and ICodedOutputStream, and rewrite CodedInputStream and CodedOutputStream to be specific to the binary format. If we want to support text-based formats, that can be a whole different serialization mechanism.

This mirrors commit 7c86bbb in the pull request to
the main protobuf project, but also reduces the size of the buffer created. (There's no point in
creating a 1024-byte buffer if we're only skipping 5 bytes...)

…han an equality check.

I wouldn't expect this to affect anything, but it appears to.

This is effectively reimplementing List<T>, but with a few advantages:
- We know that an empty repeated field is common, so don't allocate an array until we need to
- With direct access to the array, we can easily convert enum values to int without boxing
- We can relax the restrictions over what happens if the repeated field is modified while iterating, avoiding so much checking

This is somewhat risky, in that reimplementing a building block like this is *always* risky, but hey...
(The performance benefits are significant...)

…ptimize.

… - files to be killed later.

We'll probably want a lot of the code from the serialization project when we do JSON, but enough of it will change that it's not worth keeping in a broken state for now.

…field.

- Make some members internal
- Remove a lot of FrameworkPortability that isn't required
- Start adding documentation comments
- Remove some more group-based members
- Not passing in "the last tag read" into Read*Array, g

Proto3 experimental C# fork

First attempt at using profile 259 for Google.Protobuf.

…ut_service

Expose IsClientStreaming and IsServerStreaming in MethodDescriptor

Remove the C# Freeze API

Remove a few hangers-on from frozenness.

…o use it from the generated code soon.

Additionally, change it to return the value passed, and make it generic with a class constraint.
A separate method doesn't have the class constraint, for more unusual scenarios.

Throw on null for string/bytes single fields