Add property API to `GDBDebugger` This allows clients to associate custom data with debugger instance.

Autodetect GDB data directory As a courtesy to the us who use GDB from build tree, try to detect and automatically add --data-directory if no arguments are specified in GDB command (`GDBProcess gdbCommand`).

Add `GDBMIDebugger` tool to test raw MI / CLI. Useful prerry much only for `jv:libgdbs` developers.

Add (utility) `GDBProcess >> gdbCommandParseAndValidate:` to parse and validate given GDB command. This is used both by `GDBLocalProcess` and settings UI.

Fix quoting bug in `#test_directories`

doc: add `libsource-highlight-dev` to build prereqs ...as recent GDB uses it to highlight code when used in terminal.

Set `mi-always-notify` to 'on' (if supported) ...in order to get all notifications. stx:libgdbs and VDB rely on notifications being sent in order to keep internal data and UI up-to-date. If `mi-always-notify` is not supported, things may not work as espected. You have been warned!

Use most recent MI version instead of forcing MI2

Always return an architecture from `GDBInstruction >> arch`

Fix `GDBBreakpoint` description to support new-style breakpoint record ...which includes new field `locations` that contains all locations for a multi-location breakpoint. Previous versions printed more than one breakpoint on `=breakpoint-*` events (which was not valid MI syntax as documented). With this fix, `stx:libgdbs` supports both, the old and new records.