Coredump: add local/stack value typing

This change adds typing to local and stack values. Technically the type
isn't strictly necessary as DWARF should indicate how to interpret the values.

However, using types allows us to represent the lack of value, because
it has been optimized out and more complex values like reference types.

Closes #198

This change also updates links after switching to a new repo.

Coredump.md

@@ -95,16 +95,29 @@ For each thread a [Custom section], called `corestack`, is used to store the
 debugging information.
 
 ```
-corestack  ::= customsec(thread-info vec(frame))
+corestack   ::= customsec(thread-info vec(frame))
 thread-info ::= 0x0 thread-name:name
 frame       ::= codeoffset:u32
-                locals:vec(u32)
-                stack:vec(u32)
+                locals:vec(value)
+                stack:vec(value)
                 reserved:u32
 ```
 
 The `reserved` byte is decoded as an empty vector and reserved for future use.
 
+Local and stack values are encoded using one byte for the type (similar to
+Wasm's [Number Types]) followed by bytes representing the actual value:
+```
+value ::= 0x01       => ∅
+        | 0x7F n:i32 => n
+        | 0x7E n:i64 => n
+        | 0x7D n:f32 => n
+        | 0x7C n:f64 => n
+```
+
+The special byte `0x01` is used to represent a missing value, usually because it
+was optimized out by the WebAssembly engine.
+
 ## Memory
 
 The process memory is captured in the [Data Section], either entirely as one
@@ -131,17 +144,18 @@ tooling: [demo].
 [ELF coredump]: https://www.gabriel.urdhr.fr/2015/05/29/core-file/
 [Core dump on Wikipedia]: https://en.wikipedia.org/wiki/Core_dump
 [gdb]: https://linux.die.net/man/1/gdb
-[wasm-edit coredump]: https://github.com/xtuc/wasm-edit/blob/main/src/coredump.rs
-[wasm-edit]: https://github.com/xtuc/wasm-edit
-[wasmgdb]: https://github.com/xtuc/wasmgdb
+[wasm-edit coredump]: https://github.com/xtuc/wasm-coredump/blob/main/bin/rewriter/src/rewriter.rs
+[wasm-edit]: https://github.com/xtuc/wasm-coredump/tree/main/bin/rewriter
+[wasmgdb]: https://github.com/xtuc/wasm-coredump/tree/main/bin/wasmgdb
 [DWARF]: https://yurydelendik.github.io/webassembly-dwarf
 [Wasmer FrameInfo]: https://docs.rs/wasmer/latest/wasmer/struct.FrameInfo.html
 [Wasm u32]: https://webassembly.github.io/spec/core/binary/values.html#binary-int
-[demo]: https://github.com/xtuc/wasmgdb/wiki/Demo
+[demo]: https://github.com/xtuc/wasm-coredump/blob/main/bin/wasmgdb/demo.md
 [multi-memory]: https://github.com/WebAssembly/multi-memory
 [Wasm binary format]: https://webassembly.github.io/spec/core/binary/index.html
 [Data Section]: https://webassembly.github.io/spec/core/binary/modules.html#data-section
 [Custom section]: https://webassembly.github.io/spec/core/binary/modules.html#binary-customsec
 [Memory Section]: https://webassembly.github.io/spec/core/binary/modules.html#binary-memsec
 [instantiated]: https://webassembly.github.io/spec/core/exec/modules.html#instantiation
 [Global Section]: https://webassembly.github.io/spec/core/binary/modules.html#binary-globalsec 
+[Number Types]: https://webassembly.github.io/spec/core/binary/types.html#binary-numtype