Create Calendar Month Markdown Table

[MartinPacker]

Candidate syntax:

=cal November 2021
=endcal

[MartinPacker]

Actually more like =cal 2021 11.

And I think we can highlight with a CSS class particular days:

=cal 2021 11
=caldays blue 14 15 16 17
=caldays green 18
=endcal

blue and green are classes - and the day numbers would be wrapped with <span> elements with class= set.

[MartinPacker]

Added syntax:

=calnote 17 A

adds annotation to calendar entry for 17th day.

This annotation can have a <span> in it to colour it.

Also added

=calkeys blue Day we have data for

which generates a bullet coloured using class blue and text Day we have data for to act as a kind of key to colouring.

[MartinPacker]

A third parameter to =cal defines how many lines each row should occupy:

=cal 2021 11 3

Gives 3 lines in a row. The default is 2.

Here's a complete test calendar:

### November 2021
<!-- md2pptx: contentSplit: 2 1 -->

=cal 2021 12 2
=caldays blue 14 15 16 17
=caldays orange 18
=calkey blue We have data for **somehow**
=calkey orange Is focus day
=calnote 17 A
=calnote 18 <span class="green">B</span>
=calnote 4 X
=endcal

* An unrelated bullet
  * An unrelated sub-bullet

Obviously - with the md2pptx dynamic contentSplit specification - this tests well with md2pptx.

[MartinPacker]

Shipped in v0.6.