Tidier and more accessible date/time inputs

Still need to add `pattern` attributes in, and possibly hard-code
classnames into `function tsi`

Patterns:

Year: `pattern=“[0-9]{4}”`
Month: `pattern="(0[1-9]|1[012])”`
Day: `pattern="(0[1-9]|1[0-9]|2[0-9]|3[01])”`
Hour: `pattern="(0[0-9]|1[0-9]|2[0-3])”`
Minute: `pattern="([0-5][0-9])"`
Seconds: `pattern="([0-5][0-9])"`