Match by date when no time specified in TvMaze DB

[SteveErl]

Sometimes, the TvMaze database only specifies a date and not a time for an episode or set of episodes. This is most common in webChannel originated shows. In such a case, the 'Find Episode by Timestamp' syntax usually fails to find an exact or close match.
For example:
tvmaze.py -N "Criminal Minds" "2022-11-24 21:00:00"

For this episode, in the TvMaze database

   airtime =
   airdate = 2022-11-24

In this code update, we detect when no airtime is specified in the database, and apply a match-by-date behavior.

The match-by-date results are only used as a last resort. First we select exact timestamp matches. If there are none of those, we select close timestamp matches. If there are none of those, then we'll select date only matches.

For example:

tvmaze.py -N "Criminal Minds" "2022-11-24 21:00:00"
<?xml version='1.0' encoding='UTF-8'?>
<metadata>
  <item>
    <title>Criminal Minds</title>
    <subtitle>Just Getting Started</subtitle>
    ...
    <season>16</season>
    <episode>1</episode>
    <inetref>81</inetref>
    ...
  </item>
  <item>
    <title>Criminal Minds</title>
    <subtitle>Sicarius</subtitle>
    ...
    <season>16</season>
    <episode>2</episode>
    <inetref>81</inetref>
    ...
  </item>
</metadata>

Note that there were 2 episodes released on 2022-11-24, so both episodes match-by-date and appear in the above results.

In addition, a display of runtime has been added for the -M invocation option. For example

tvmaze.py -M "Fire Country"
<?xml version='1.0' encoding='UTF-8'?>
<metadata>
  <item>
    <title>Fire Country</title>
    ...
    <inetref>60339</inetref>
    <collectionref>60339</collectionref>
    <language>en</language>
    <releasedate>2022-10-07</releasedate>
    <userrating>6.300000</userrating>
    <popularity>99.0</popularity>
    <year>2022</year>
    <runtime>60</runtime>
    ...
  </item>
</metadata>

Resolves #654

Checklist

• contribution does not duplicate one of our existing pull requests
• contribution is in a branch rebased against master
• code follows the MythTV Coding Standards
• documentation added/updated/removed where necessary
• commits are logically organised and have good commit messages