replace deprecated (as per jQuery 3.x) methods -- fixes #1163

[hagman]

Testing the code against the jQuery Migrate Plugin (current version: 3.4.1) reveals a few deprecated functions. Accordingly,

• replace .someUiEvent(func) with .on('someUiEvent', func)
• replace .someUiEvent() with .trigger('someUiEvent')
• replace .isFunction(arg) with typeoff arg === 'function'