Use thumbnails from "media_hash_thumbnail" table (#2031).

[wladimirleite]

Closes #2031.

[wladimirleite]

Added other minor fixes and improvements related to WhatsApp generated HTML.

[wladimirleite]

I created this PR just to address #2031.
However, while working on #2030, I realized that there may be some merging conflicts between them.
And the main problem is that I started to use two phones to check #2030 (initially I had only a WhatsApp database), comparing parser results with actual messages displayed on the devices. And there are differences that were solved by #2031, but I am not seeing them in #2030.
So I am closing this PR and will create a new one, which will handle both issues (and maybe #1923) together.

[lfcnassif]

Hi @wladimirleite! I can merge #1920 to avoid more merge conflicts with the improvements you are working on. I detected just very minor differences with master, so I think it's safe and I can take a closer look at them later. What do you think?

[lfcnassif]

PS: I saw you already pushed a few commits, so not sure if it will help.

[wladimirleite]

Please, do that if you can.
I can stop commiting and reverse merge with the master after you merge #1920.
This should avoid more conflicts.