- no highlight for non-targets
- make dragged node a non-target

Where applicable, replace
  getObjectById(repr->attribute("id"))
with
  getObjectByRepr(repr)

Also add warnings pragma.

Function was actually broken for a long time, see
  !1586
Probably did not work since
  1eacfbf3 or even
  f11a0302
(so likely did never work properly in gtk3)

Proper way to do this (if it's still desired) should likely be
through CSS (the smaller font size is irrelevant for Adwaita, though)

Remove unneeded ege functions.

This reverts commit d0d3c000

Fix a issue in mirrorsymmetry that make wrong display if the cut line first corosing is previous in the cutted path

Follow-up for bed10a8f

Did not properly respect document scale.

Also add ensureUpToDate(); not sure if it's required, but it's used
everywhere else in the code, so seems safer this way.

Follow-up to 205241f2
Fixes #1175

Fixes #159

Further improvement for 4f04e473

Use glib functionality for retrieving a list of preferred locales.

In particular this allows "systemLanguage" handling to work properly
if LANG and similar environment variables are not set (the default
on Windows).

- replace usage of deprecated `TimeVal` with `DateTime`
- Add `-DGLIBMM_DISABLE_DEPRECATED` for strict build mode

* --export-margin did not work if exported area is the page, i.e.
  export with --export-area-page or normal export without --export-id
* --export-margin did not work when both --export-id and
  --export-area-drawing were given

Fixes #1022

Calculate effective export DPI first (affected by both
--export-height and --export-width) before calculating width/height
for export.

Previously width calculation did not consider the effective DPI
value resulting from --export-height specification

Fixes #1135

Different display units, or transforms on groups
no longer affect inset/outset operations.