Do not convert spaces to tabs in verbatim

I should mention this is only seen in leading spaces.

Also, the discrepancy in source (4 spaces) and display (8 spaces) makes it impossible to line up text in verbatim blocks that need 8n+m leading spaces, for integers 0≤n and 4≤m≤7.

I can confirm this in Zim 0.62 on Debian 7. I frequenlty use Zim to store code and configuration snips pasted from other files. I use 4 space indentation with spaces in my files and find myself constantly adjusting how it looks in Zim just to get it to look okay. Recently I've started using Vim to retab the contents before pasting into Zim. I might would consider using the code plugin, but it doesn't seem to have a plain text choice.

I think that the bug description contains a vital clue to both the issue and (IMO) the solution.

Both the OP and myself think of 'verbatim' in terms of *blocks*... in fact, it sooo does not make sense to me that verbatim might be applied to *part* of a line that I had to test it before writing this comment.

Relatedly, I think the issue with the leading space is actually a workaround to satisfy the wiki markup parser, which would not like "<verbatim><whitespace>"... so we use "<whitespace><verbatim>".

Particularly if you take into account any workflow which might need to get *BACK* verbatim output (e.g. from the *.txt file, like log entries, etc)... the correct implementation should be to manage verbatim regions as *blocks* instead of spans.

I also checked, and using a three-single-quote (on their own line) *DOES* currently yield a block quote; with a side effect of indentation... but (at a wiki-source level) it *already-works* as expected! :)

That means that the only real issue, IMO, is that the verbatim tool uses the two-single quotes rather than the whole-block-of-lines block quote.

https://github.com/jaap-karssenberg/zim-desktop-wiki/issues/49