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>`
The issue occurs because of svg pretty formatting - indent spaces <text> tag treats as actual spaces. Because of that use some css magic to remove those spaces from <text> tag and assign class to it's children <tspan> tags.
Altough trying to solve this issue I've tried to disable svg pretty format and got empty svg as a result (only templates, styles, no annotations) for some reason.
Refactored a code a bit and replaced literal parsing with `text_obj.BIMTextProperties.text` since it's already done beforehand in `tool.Drawing.update_text_value()`.
TestExportTextLiteralAttributes and TestImportTextAttributes was failing because now we're assuming that BoxAlignment will have 1 of values from the list below and not "BoxAlignment"
"top-left", "top-middle", "top-right", "middle-left", "center", "middle-right", "bottom-left", "bottom-middle", "bottom-right"
Added drop down menu to Ifc Text section in object properties where you can change text's size and it will automatically change it in `EPset_Annotation.Classes`. You can also preview it in viewport and it will write in IFC only after you finish editing.
Still need to investigate `annotation.Annotator.resize_text(context.active_object)` in `refreshFontSize`.
1) Puts IFC Text only on top of ifc panels to make it easier to change it's text
2) I guess it could be a good practive to set `bl_order = 1` by default so it will be possible later to prioritize something since by default blender sets `bl_order = 0` and then even `bl_order = -1` wouldn't help.
3) May not work in previously created files
Dion Moult
