Printing: fix text resolution

Scintilla doesn't respect the context resolution, so we need to scale
its draws ourselves.
Printing: draw the vertical separator line more accurately

Use the dimensions and offsets used by Scintilla to position our
separator line, since its position depends on where Scintilla drawn.

Closes #3580268.
Printing: fix improper margins when printing to a physical device

We were improperly adding the printing device margins to the area
where we print, leading to wider margins on physical outputs than
on PDF or preview outputs (which have no hard margins), as well as
wasting space and not respecting user's settings.

Closes #3580269.
Parse scope for D nested template blocks (#3582833)
Fix reStructuredText comment marker

Closes #3585377.
Move D, Vala unique keyword aliases out of keywordTable

Instead put them in initialize*Parser().
Never strip trailing spaces for Diff documents
Scroll cursor in view after line breaking
Add Asciidoc filetype with symbol parser

Add an Asciidoc filetype and a basic symbol parser based on ReST.
See the FIXMEs for ReST to Asciidoc changes still to be done.
Fix a typo insode geany.glade
Update of Dutch translation
Fix cancelling Project Close when showing the unsaved changes dialog
Fix sci_get_contents() buffer length parameter name & doc

sci_get_contents() takes buffer length as a parameter, not the
number of characters to copy. Buffer length includes a null byte.
Make sci_get_contents() accept -1 for buffer_len to get all text
Remove 'Open file in a new tab' save as option
Add 'Document->Clone' menu command

This copies the current document text and properties into a new
document, similar to the old Save As 'Open file in a new tab'
option, but easier to understand and decoupled from saving.

One notable difference is that the new document does not copy the
filename - the old behaviour was confusing and error-prone for the
user (e.g. editing two documents with the same filename).
Disable 'Save As' dialog Rename button unless document exists on disk
Mark cloned documents as modified

This helps avoid accidental data loss.
Clone line breaking, auto indent, indent type, indent width settings
Update manual for Document->Clone command