Show multimedia tile to support text formats

[tonyforster]

Enhance the show multimedia tile to support as many formats as possible including txt, doc, pdf etc.

[walter]

more fine-tuning suggestions from Tony...

One (of probably many) inconsistency: I use scale for all show media
except text, for which I have set-text-size (and set-text-color)
blocks on the Pen palette. Maybe it should scale relative to the
current text size?

Doesnt worry me, once I realised that scale just applied to show I was happy.

Related issue is the labelling and grouping on the tabs:

hideblocks might be better on the turtle tab with clean

is multimedia show better on the templates tab? are all the templates needed if we now have multimedia show?

does print belong on the numbers tab, maybe turtle or redbox?

Redbox tab label "keyboard" is misleading, other or extra?

hover tips or right click tips a good enhancement?

[walter]

I think the hideblocks is really only relevant to slideshows, hence it is on the templates palette.

The show brick is of general utility, so I think it should stay on the Turtle palette.

I don't have strong feelings about print, so I think I'll leave it where it is.

I renamed Keyboard to Extras as per your suggestion.

Hover is being handled in a separate ticket (by rgs)

[walter]

oops. reopening because I still need to add provisions for txt and pdf as per the original ticket.

[walter]

there is more work to do re formating which I will defer to 0.90, but .txt, .py, and .lg files will open with the show block.

[walter]

Version 104 now has support for .rtf. Still need to do .doc and .odt.

[walter]

added simple RTF support to show block

[walter]

I don't see the use case for adding additional formats. Will reopen if a compelling use case is proposed.