wasmtime-execute is now wasmtime-jit. Move `JITCode` and the TargetIsa
into a new `Compiler` type. `InstancePlus` is no more, with trampoline
functionality now handled by `Compiler`.
And lots of other miscellaneous changes. Rename InstanceWorld to
InstancePlus and reorganize its contents. This still isn't a great name,
but at least now it has a clear purpose.
This implements a minimal wast testing harness in tests/wast.rs, which
runs the wast tests under tests/wast.
It also adds tests for trapping in a variety of ways, and fixes several
bugs exposed by those tests.
The memmap crate doesn't make it straightforward to have part of the
region be writeable and part readonly. Since this is a fairly boutique
use case, and we don't need all that much code, just use the low-level
APIs directly.
Also, introduce a concept of "tunables" for adjusting the parameters of
the runtime.
The biggest change is the split from FunctionIndex to
DefinedFuncIndex to FuncIndex. Take better advantage of this by
converting several Vecs to PrimaryMaps.
Also, table_addr can now handle indices of the table index type,
so we don't need to explicitly uextend them anymore.
