This change alters the small square dot cursor to a more visible 16x16
cursor for X11. A new option `spice:largeDotCursor` can be set to use an
alternative 32x32 cursor for the vision impaired.
This brings nanosvg into the project for SVG loading and rendering.
Unfortunatly we can not at this time use a submodule for this project
until https://github.com/memononen/nanosvg/pull/214 is merged.
Many X11 window managers will present an application on their
taskbar as a combination of the application name and an icon
imagery pulled from the X-Property _NET_WM_ICON. Applications
built under frameworks such as Qt or GTK have this property
populated by the framework. This commit adds the Atom _NET_WM_ICON
and populates it with a 64x64 icon of Looking Glass.
