☂️ Fix importer parsing errors

[daem-on]

Umbrella issue for #11, #9, #7

The wtherion importer for TH2 files makes some assumptions based on the thbook specifications, some of which are incorrect.
Not everything follows the same patterns and maybe the whole option parser needs to be rewritten.

[CaverBruce]

Checking beta version

Imported to WT beta a th2 created by XTherion, saved in WT, exported to th2 then compared to original th2.
The file contained 7 scraps, 4 xvi files and 1 scanned image.
It is more complicated than is typical for me - usually I only load 1 xvi or scanned image. Have attached both versions of the file.

A few things apparent:

• The scraps objects and xvi are coincident (ie correct), but the scanned image has an offset, similar or same as XVI images not placed in the correct position #5
• Both export and export as (th2) save the file twice (asks for a filename twice and two files are saved - both identical).
• issue not all scrap metadata survives round trip from th2 to WTherion to json and back #7 still live, as discussed therein
• issue line context is not correctly produced (th2 to json to th2) #9 resolved and closed
• issue -text string truncated at apostrophe #11 not entirely resolved, as discussed therein
• Two double quotes are produced whereas only one double quote should be present. But there are exactly similar examples that are correctly formed in the same file.

3-HawkesPlan-exported from WTherion.th2.txt
3-HawkesPlan-created with XTherion.th2.txt

[daem-on]

@CaverBruce Thanks! Seems like the fixes I implemented were not at all enough, but these issues should be fixable. Like I said, I don't have a lot of time right now, maybe next week I'll be able to work on this. Thank you again for the testing and feedback.