Haketilo

stop haketilo() fixture cleanup from closing last browser window

validate repository responses against JSON schemas

• compute_scripts.awk (include_file): don't enforce specific path format on #INCLUDE'd files
• .gitmodules, schemas: add Haketilo JSON schemas subrepo
• html/install.js (InstallView): import schema validator and run it against downloaded mapping and resource definitions...

fix URL construction when downloading definitions from Hydrilla

make "uuid" an optional property

automatically pick up a free port to run the HTTP proxy on

It is now possible to run multiple make test commands in parallel (e.g. testing abrowser and librewolf simultaneously after running configure for each of them in 2 different directories).

fix test-environment* targets

fix out-of-source builds

improve the build system

assume and use "$schema" properties in item definitions

facilitate running test environment with Haketilo loaded into browser