To make the simulator work without modification for more PRs use the
original `lv_conf.h` file and modify the needed parts for the simulator.
Furthermore use globbing expressions to add all available fonts and
icons in case a PR adds new fonts or icons.
When pressing `i` create a screenshot of the current InfiniTime screen
by dumping it to a timestamped png or bmp file like
`InfiniSim_2022-03-08_203421.png`.
Add a new configure option `WITH_PNG` with default `ON`. When switched
to `OFF` the screenshots will be created in `bmp` format.
Fixes: https://github.com/InfiniTimeOrg/InfiniSim/issues/5
With the old default of just "InfiniTime" you have to have the working
directory in the `InfiniSim` directory. The new default makes the
default independent of the current working directory.
