release v2.3.0 -- adding support for negative values

Angular v10/v11 version

Release v3.1.0 -- adding support for negative values

merges pull changhuixu#49, thanks @krzysztof-zych

update to Angular v12; release v3.0.0

update solution npm package dependencies

release v2.2.3

update dependencies versions for the demo app

update app to Angular v10.2.0; release library v2.2.1

Release v2.2.0

for better international support, both `mask` and `digitOnly` directives now also check the `code` attribute in `KeyboardEvent`.
fix changhuixu#35

Release v2.1.0

closes changhuixu#39

Release v1.9.0

fix changhuixu#39 by cherry-picking changhuixu#40
v1.9.0 is compatible for projects using Angular versions 6-9

upgrade library and app to Angular 10

release v2.0.0
closes changhuixu#37