[planner] (32 commits) ...Merge branch 'gtk3-port' into 'master'

[Mart Raudsepp <mraudsepp src gnome org>]

Summary of changes:

  b6be957... list-model: Fix get_path vfunc implementation
  d03fcfc... python: Drop gtk2-based legacy python plugin and bindings
  923f9e9... libgnomecanvas: Import gtk3 ported version source code from
  ca2e803... libgnomecanvas: Change evolution-config.h include to ours
  a958918... libgnomecanvas: Restore GnomeCanvasPoints
  224f7c9... libgnomecanvas: Restore various utility functions used by G
  fb36099... libgnomecanvas: Import GnomeCanvasLine from older evolution
  e40aad1... libgnomecanvas: Fix building of GnomeCanvasLine copy
  89b0153... libgnomecanvas: Drop unnecessary gnome-canvas-i18n.h header
  fd4e332... Port to GTK3 and adapt to changes in imported libgnomecanva
  2ffdb1d... build: Pass GTK_VERSION_{MIN,MAX}_REQUIRED for compilation
  73d75c6... build: Update version to 0.14.90
  14b1051... cell-renderers: Adapt to GtkCellRendererClass vfunc const c
  d7088b7... gantt-row: Stop using deprecated gdk_cursor_unref
  4374f46... charts: Restore default white background via GtkStyleContex
  5de6777... charts: Port font width factor updating to GtkStyleContext
  6c41070... Preliminary port to GtkStyleContext
  da72059... Fix some signedness warnings
  f8fa370... Fix remaining adjustment related deprecation warnings
  a49e7e8... Port away from deprecated gtk_widget_size_request
  d4043fb... Drop keyboard/mouse regrab hacks after combo choosing in po
  055e4bf... gantt-row: Drop usage of deprecated gdk_window_get_pointer(
  f23a033... build: Require >=gtk+-3.2
  cffbd2a... Handle GTK 3.2 deprecations
  2079b52... Handle GTK 3.4 deprecations
  aa15218... build: Require >=gtk+-3.10
  4921044... Make use of gtk_builder_new_from_resource() from GTK 3.10
  e10b9ae... gantt/usage-view: Restore ctrl+mousewheel zoom on chart are
  62acb30... canvas-line: Don't force bounds calculation skipping or not
  85da18d... gantt-row: Draw relationship drag lines with a line width s
  653e328... libgnomecanvas: Fix cairo port of GnomeCanvasLine
  1eda641... Merge branch 'gtk3-port' into 'master'