Support 'vertical' Workspace warping

'Vertical' Workspace warping is a variant of the existing Workspace
warping feature: When a user drags a window to the edge of the Screen,
the window is warped to the next / previous workspace.

'Vertical' Workspace warping detects a drag towards the upper / lower
border of the screen and warps the current workspace about an 'offset'.
Example given, lets say the user has 9 workspaces and considers them to
form a 3x3 grid:

  +-+-+-+
  |1|2|3|
  +-+-+-+
  |4|5|6|
  +-+-+-+
  |7|8|9|
  +-+-+-+

An 'offset' of 3 warps from workspaces 2 to workspace 5 (or 8), when a
window is dragged to the bottom / top border.

New configuration ressources:

    session.screenN.workspacewarpingvertical: true
    session.screenN.workspacewarpingverticaloffset: X

1 files changed, 2 insertions, 0 deletions

diff --git a/src/Screen.hh b/src/Screen.hh
index 30fbb4a..15eb349 100644
--- a/src/Screen.hh
+++ b/src/Screen.hh
@@ -95,6 +95,8 @@ public:
     bool isRootColormapInstalled() const { return root_colormap_installed; }
     bool isScreenManaged() const { return m_state.managed; }
     bool isWorkspaceWarping() const { return (m_workspaces_list.size() > 1) && *resource.workspace_warping; }
+    bool isWorkspaceWarpingVertical() const { return *resource.workspace_warping_vertical; }
+    int getWorkspaceWarpingVerticalOffset() const { return *resource.workspace_warping_vertical_offset; }
     bool doAutoRaise() const { return *resource.auto_raise; }
     bool clickRaises() const { return *resource.click_raises; }
     bool doOpaqueMove() const { return *resource.opaque_move; }