examples: fix a bug with decimals in calculator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples: fix grid size for buttons in calculator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples: improves decimal display in calculator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples: adds a 'C' button to the calculator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples: fix the display of "," when there are no decimals

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
examples: adds tests for the 'C' button and multiple decimals in the calulator

Signed-off-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>