The default encoding for source files is UTF-8 since Python 3, so we can
drop all encoding headers. While we are at it, just replace them with
SPDX headers.
This shouldn't make a difference in normal dosage usage (since dosage
exits right after this anyways), but it removes hidden dependencies
between tests and might help when embedding dosage into other Python
software. As a side effect this gets rid of some global state, so
running dosage multiple times in the same process is more reliable...
Since we already match comics case-insensitive on the command line, this
was a logical step, even if this means changing quite a bit of code that
all tries to resolve the "comic directory" in a slightly different
way...
This is a first step for #42. Since most access to the scraper classes
is through instances, modules can now dynamically override url and name
(name is now a property).
This is modeled parallel to the "adult" feature, except the user can't
override it via the command line. Each comic module can override the
classmethod getDisabledReasons and give the user a reason why this
module is disabled. The user can see the reason in the comic list (-l or
--singlelist) and the comic module refuses to run, showing the same
message.
This is currently used to disable modules that use the _ParserScraper if
the LXML python module is missing.
