Add asBytes() and asChars() methods to array classes to reinterpret-cast to bytes / chars, since this happens all the time and is otherwise a huge pain.

Use the new methods in a bunch of places.

Extended discussion:
https://groups.google.com/d/msg/capnproto/lRlWBOglQv4/8-Qo96AcZQIJ

See changes to test.capnp for example.

Currently only supported through generated code, not in the dynamic API. Not exactly sure how to expose this in the dynamic API...

Note that embedded schema structures in generated code are still incorrect.

For portions currently copyright by Kenton (most of it), transfer copyright to Sandstorm Development Group, Inc. (Kenton's company).

The license change is practically meaningless, as MIT and BSD 2-clause are legally equivalent. However, the BSD 2-clause license is sometimes confused for its ugly siblings, BSD 3-clause and BSD 4-clause. The MIT license is more immediately recognizeable for what it is.

Rémy Blank and Jason Choy (the two non-trivial contributors) are on record as approving this change:

https://groups.google.com/d/msg/capnproto/xXDd2HUOCcc/gbe_COIuXKYJ

Extend totalSizeInWords() to also return a count of capabilities, which helps when a separate capability table needs to be allocated as well.  Use this in the RPC system.

Remove 'has' for primitive fields.  Dynamic version always returns true.  This also means that primitives are always included in text format, even if they are default-valued.

Interface code generation.  Also update method grammar to allow multiple returns, and allow specifying request/response structs instead of parameter lists.

Extend interface grammar to support inheritance, and update compiler to properly compile interfaces.

Revamp generated interface to Object fields.  Now there is an ObjectPointer::{Reader,Builder}.  This will simplify the dynamic API (next change) and also makes it easier to delegate decisions about the object type to a function that doesn't know about the context where the object lives (i.e. by passing an ObjectPointer::Builder).

Rename non-group again, now to 'slot', which is much nicer.  Also introduce fixed lists as a third kind of field (but not implemented yet).

New method isFoo() exists for union fields only and returns true if foo is the active union field.

Unnamed unions WIP.  About to change MemberInfo format, which will require re-bootstrapping the code generator.

Allow SchemaLoader to use a callback to lazily load schema nodes, including dependencies of loaded nodes.

Enable some useful Clang warnings, fix some bugs it detected.  Especially, eliminate all dynamic initializers.