Incorporate PR #39: Change several member functions to const & add so…

…me initial values.

Closes #39.

Change architectures to "*" in library.properties.

Closes #37.

Add JC_Button to keywords file so that syntax highlighting works on #…

…include statement. Closes #25.

Closes #22.

Add ToggleButton derived class.

Fix constructor initializer list order. Closes #14.

Typo in README file.

Rename library & repository from Button to JC_Button.

Add library.properties file.

version 1.0