Giveaway Extractor: fix bug that does not extract giveaways from comments when running with "extract onward" enabled

[Eiion]

Description
1, If you go through e.g. the community train and the next giveaway link is not yet in the GA description but in the comments below, the extractor does not recognize this and stops extracting at that point.
(Example: https://www.steamgifts.com/giveaway/QGIUX/shards-of-azuria - the link in the comments is not yet added to the description as "next" and this happened with most (probably) all the other wagons as well where the description was not updated to the next link in the comments, yet.)

2, The giveaway extractor does not recognize some links to next giveaways
(Example: https://www.steamgifts.com/giveaway/OfTxR/pillars-of-eternity - for whatever reason the extractor does not recognize the next link. This also happened before with other wagons.)

Steps to Reproduce

1. Go to the current community train or check examples
2. Click on "Extract all giveaways (specify parameters)" ("Only extract from the current giveaway onward." activated)
3. See error

Expected Behavior
All links, no matter if in the description of a giveaway or the giveaway's comments get listed by the extractor and used to progress in the train.

Console Errors
none

Screenshots
Example 1:

Extraction 1:

.
Example 2:

Extraction 2:

System (please complete the following information):

• ESGST Version: Extension v8.5.5
• Browser + Version: Chrome v77.0.3865.90 (Official Build) (64-Bit)

[rafaelgomesxyz]

For the second case, it's because "onward" is not in the default regex for looking for next links, only "onwards" is. Go to the Giveaway Extractor settings and change it to this: forw|more|next|onwards?|►|>|→