added todo list and updated readme

README

@@ -13,7 +13,9 @@ To build, simply run qmake and make.
 To configure, you can set in the file ~/.panorc the following options.
         shader_dir=<path to directory containing the shader files>
         image_file=<path to the desired input file>
+        max_fov=<starting value of max_fov, in degrees>
 Lines in the file must start with option names, and no spaces should go
 between option names, equal signs and values. If no shader path is set, the
 default is ./shaders/. If no input file is set, or the file is missing, a
-file chooser will be shown at startup.
+file chooser will be shown at startup. The default value of max_fov is 60
+degrees.

TODO

+Higher priority:
+-Study singular points of the transformations and fix the image in those
+cases.
+
+Lower priority:
+-Discretize grid, add a parameter grid_discr=5x5, 10x10, 15x15, ...
+-Add a parameter for the grid resolution.
+-Compute a limit for the discretization (298 degrees?).
+-Change squares by triangles on the top and on the bottom of the sphere.