XF2 Add-on Notice Time Replacables 2.2.0

[virgilio183]

Adds the following replaceable to notices:

• {time_start:absolute}
• {time_start:relative}
• {time_end:absolute}
• {time_end:relative}

These tags pull from the date-time criteria options for when to start/top showing a notice.

Absolute times are displayed in the user's timezone.

Fully phrased compared to the XF1 version.