Tests: Build a test suite for layouts

[tony]

We need to build a robust test suite to ensure these render perfectly:

• Preset layouts

  • even-horizontal
    Panes are spread out evenly from left to right across the window.

  • even-vertical
    Panes are spread evenly from top to bottom.

  • main-horizontal

    A large (main) pane is shown at the top of the window and the remaining panes are spread from left to right in the leftover space at the bottom. Use the main-pane-height window option to specify the height of the top pane.

  • main-vertical

    Similar to main-horizontal but the large pane is placed on the left and the others spread from top to bottom along the right. See the main-pane-width window option.

  • tiled
    Panes are spread out as evenly as possible over the window in both rows and columns.

• Normal layouts, e.g. bb62,159x48,0,0{79x48,0,0,79x48,80,0}

CC: #800 #793 #667