1) Leaders text decorator wasn't changed after adding support for multiple literals
2) added drawing data update on toggling viewport annotations - so user would see correct values right away; also fixed similar thing on updating product
1) changed first ifc saving handler from save_pre to save_post so that in the situation when you just created with .blend file and started ifc project on save dialog would suggest the same name for the .ifc file and for .blend file (previously it was always suggesting ".ifc" and you had to type it in manually).
2) suggested default ifc project named changed from `<blend_filename>.blend.ifc` to `<blend_filename>.ifc` for simplicity.
PS save_pre didn't really work anyway - by the time "save ifc dialog" file was invoked and appeared .blend file was already saved anyway.
Added option to store multiple literals inside 1 Ifc text object.
If multiple literals share the same `BoxAlignment` then only the first one will be displayed in viewport
to prevent visual clutter (although added small asterisk symbol to indicate that there are still multiple literals).
Added option for aggregated text annotations. Example - "door-tag" symbol.
If you create text, specify "door-tag" symbol in EPset_Annotation.Symbol
\and add two literals to it then they'll automatically will fit to that door-tag in the svg drawing
(https://i.imgur.com/OXaIlWe.png).
The way it works - you define symbol in symbols.svg (or in your own symbols svg file)
and then add the `<text>` fields where text from literals will fit right in.
The imporant note: `<text>` tag must have attribute `data-type="text-template"` for it to work.
For example: `<text text-anchor="middle" dominant-baseline="middle" data-type="text-template"></text>`
Andrej730
