Examples should run entirely by default unless flags are given

[FabienPean-Virtonomy]

Following up the live discussion: the way program options are handled should be modified. Examples without program options should run the whole sequence, while flags allows to specify specific behavior.

./example # should run particle generation/relaxation + timeloop
./example -r=true # should run just generation/relaxation
./example -i=true # should just reload

Program options should also be following more standard format with dash followed by single letter and double-dash followed by whole words. Since sphinxsys has 3 options that starts with R, it would be preferable to only allow whole word writing to avoid confusion and error.

./example --relax 
./example --reload 
./example --restart

Effects:

• Easier for newcomer to test examples
• Can simplify several CMakeLists by reducing duplication