[meld] (52 commits) ...Merge branch 'flatpak-ci' into 'master'

[Kai Willadsen <kaiw src gnome org>]

Summary of changes:

  dea3af2... Experimental pass at flatpak CI (*)
  c2814be... Update to optimistically use the master runtime (*)
  e3fb7e3... Update comment for flake8 (*)
  513764e... data: Update gtksourceview to current requirement in flatpa (*)
  baae375... data: Update flatpak build to use meson (*)
  01d5bc1... data: Validate appstream with no network interaction (*)
  faa4a63... First pass at syncing app IDs (*)
  19b17f8... Rename flatpak build file (*)
  8826ea5... Merge branch 'master' into flatpak-ci (*)
  1428bae... data: Prettify JSON formatting (*)
  32e395f... Make application ID (partly) configurable (*)
  732438c... Remove unnecessary defaults from About dialog UI file (*)
  4b533c8... Make icon name a new configuration constant (*)
  a2bb731... Update copyright in About dialog (*)
  216059f... Add currently-unused Meson options for development release (*)
  b44c388... Update flatpak file with devel-mode application ID (*)
  0dfbeec... Add review and nightly configuration for flatpak builds (*)
  2421ba6... Fix meson options to be consistent with the flatpak build (*)
  a3a345d... Sync app IDs in CI build (*)
  a074038... Remove remaining meld.css build system references (*)
  41d0ae2... Merge branch 'master' into flatpak-ci (*)
  f6c59dc... Remove unneeded icon theme setup (*)
  a1b8a62... meldwindow: Add theoretical support for devel styling (*)
  5a67a9c... Update application ID to be profile-based (*)
  ad1f978... Make our desktop file templated for profile-based icon use (*)
  095b46c... Make most resources load from the resource (not application (*)
  8d975b0... meld: Move conf.py to be meson templated and add import hac (*)
  f6f8301... meld.conf: Template out our runtime config file at build ti (*)
  4715f1a... meldapp: Remove the separate icon identifier (*)
  680030f... test: Duplicate conf.py.in hack for unit tests (*)
  9c9fe68... data: Fix desktop file variable (*)
  d6d85f8... data: Ideally these icons would be application based, but t (*)
  3078091... conf: Have the resource base reflect reality (*)
  5bef61c... Unquote profile in conf templating (*)
  6b868b2... Update win32 build for conf.py change (*)
  04ba793... build_helpers: Partially fix setup.py build (*)
  a4824bd... Make appdata correctly template the application ID for desk (*)
  2c9680f... meldapp: Move custom CSS provider initialisation into MeldA (*)
  12ba9c5... misc: Remove global app access (*)
  9a64c25... meldapp: Remove global app singleton and adjust start scrip (*)
  bd05c54... bin/meld: Refactor our entry point to be saner (*)
  03e97af... setup_win32: Sync some metadata from the main setup.py (*)
  5e7ec06... setup.py: Remove python version check (*)
  1506975... setup.py: Pull meld.conf import hack from setup_win32.py (*)
  b0d03b3... bin/meld: Rewrite dependency checking logic (*)
  93505d9... Update dependency list in meson build (*)
  b9cd307... bin/meld: Revert a translation string for ease (*)
  32aa8c0... Fix meson script's Python version check (*)
  1230f90... Update README for Meson and other distribution changes (*)
  3a4ae73... CI: Remove deprecated CI jobs (*)
  ddabed0... CI: Put flatpak creation in a custom stage for ordering (*)
  b0e8152... Merge branch 'flatpak-ci' into 'master'

(*) This commit already existed in another branch; no separate mail sent