map-layer: Implement continuous zoom

The map layer now accepts fractional zoom levels by scaling the entire
map layer with gtk_snapshot_scale().
2 jobs for continuous-zoom-scale in 11 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
failed #1287673
fedora

00:00:11

failed #1287672
fedora

00:00:07

 
Name Stage Failure
failed
fedora Build There has been a runner system failure, please try again
Running with gitlab-runner 13.10.0 (54944146)
on gcc176 1ZxLvhuY
Preparing the "docker" executor
Using Docker executor with image registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28 ...
WARNING: Container based cache volumes creation is disabled. Will not create volume for "/cache"
Authenticating with credentials from job payload (GitLab Registry)
Pulling docker image registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28 ...
WARNING: Failed to pull image with policy "always": Error response from daemon: manifest for registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28 not found: manifest unknown: manifest unknown (manager.go:205:1s)
ERROR: Job failed (system failure): failed to pull image "registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28" with specified policies [always]: Error response from daemon: manifest for registry.gitlab.gnome.org/gnome/gtk/fedora-base:v28 not found: manifest unknown: manifest unknown (manager.go:205:1s)