It gives warnings when running `gulp locale`, in a previous patch it was
explicitly asked to remove it and there is quite a bit of discussion
about the validity of the locale at
https://bugzilla.mozilla.org/show_bug.cgi?id=418485. In short, let's
remove it to prevent these issues.
This builds on the scrolling mode work to add three buttons for joining
page spreads together: one for the default view, with no page spreads,
and two for spreads starting on odd-numbered or even-numbered pages.
Please note that this patch *purposely* doesn't add every standard (or semi-standard) page name in existence, but rather only a few common ones. This is done to lessen the burden on localizers, since it's quite possible that all of the page names could need translation (depending on locale).
It's easy to add more standard page sizes in the future, but we should take care to *only* add those that are very commonly used in actual PDF files.
The units are currently repeated after each dimension, which seems unnecessary and is also not done in other PDF viewers (such as e.g. Adobe Reader).
Furthermore, the name of the l10n arguments can be simplified slightly, since the name of the strings themselves should be enough information.
Finally, the `width`/`height` should be formatted according to the current locale, as is already done for other strings in the document properties dialog.
This required changing the import script in two ways:
- we should use the `default` branch and not the `tip` tag since the
latter may refer to another branch than `default` (this is the case for
the `vi` locale, which caused in the files to be overwritten with
incorrect contents since `tip` referred to the
`THUNDERBIRD600b1_2018031614_RELBRANCH` branch);
- we should check if the response code is indeed 200 because recently a
script removed all empty localization files upstream (refer to
https://bugzilla.mozilla.org/show_bug.cgi?id=1443175).
With the current way that the `HandTool` is implemented, if someone would try to also add a Zoom tool (as issue 1260 asks for) that probably wouldn't work very well given that you'd then have two cursor tools which may not play nice together.
Hence this patch, which attempts to refactor things so that it should be simpler to add e.g. a Zoom tool as well (given that that issue is marked as "good-beginner-bug", and I'm not sure if that really applies considering the current state of the code).
Note that I personally have no interest in implementing a Zoom tool (similar to Adobe Reader) since I wouldn't use it, but I figured that it can't hurt to make this code a bit more future proof.
