Add Component Map section to CalendarStyle documentation.

The Component Map is a color-coded legend of the components in the
style. The format is:

<color-coded image showing sections of style>

<table of color-component URL pairs>

Change-Id: I0e6e4577516669515c083e58a8f875e344f7bdf7
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>
Reviewed-by: Jens Bache-Wiig <jens.bache-wiig@digia.com>
Reviewed-by: Jerome Pasion <jerome.pasion@digia.com>
Use childAt() instead of cellIndexAt().

Change-Id: I74ee716620d31363bccaade89d51aa23d3b39830
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>