Mass rename 'reference' -> 'pointer'.  Been meaning to do this for a while -- all the documentation talks about 'pointers', not 'references'.

Dynamic API mostly done...  not tested.  This commit actually starts embedding the schema data in the generated code.

Restore ability to upgrade from List(Bool) to List(T) where T is a struct whose @0 field is of type Bool.  I previously disallowed this to reduce complexity, but it turned out to actually increase complexity.

Delete Code Friday:  Inline structs/lists/data are too complicated for not enough benefit.  There goes a week of my life that I'll never get back.

Implement code generator plugins.  The Cap'n Proto compiler, when given -o foo, invokes the binary capnp-foo and passes the schema, in Cap'n Proto format, to its stdin.  The binary is executed with the current working directory set to the desired output directory, so all it has to do is write the files.

Implement 'Object' field type, which can be any pointer type.  The caller specifies the type when calling the accessors.

Detect and disallow List(Inline(Bool, n)) as it is not currently implemented correctly (and may be difficult to implement correctly-yet-efficiencly).

Correctly handle inline fields that aren't present in the parent struct (i.e. because we're reading an older version of the struct that lacked those fields).

Improve unions.  Members of a union are now scoped within the union, although they share ordinal space with the parent struct.

Make enum syntax match docs, make enum lists work correctly, add enum tests, enforce maximum ordinals on enum values and interface methods, change the maximum field ordinal to 16-bit to match docs (now all ordinal limits match).

Basic code generation starting to work.  My machine just did something weird so I'm submitting and pushing in case of imminant hardware failure...