plus these fixes:
* adds a previously missed libvips optimization,
giving much smaller files at the same quality
* try to align the quality-scale of each backend
(pillow, libvips, ffmpeg) by filesize
hooks returning exitcode 0 will:
* run the next hook, if any
* allow the original action, unless successive hook opposes
hooks returning exitcode 100 will:
* abort running successive hooks
* allow the original action
hooks returning anything other than 0 or 100 will:
* abort running successive hooks
* REJECT the original action
zmq can now respond with json; a dict with "rc", "rejectmsg",
"reloc" and so on, just like other hooks replying with json
on Windows and Macos, most filesystems are case-insensitive,
which can lead to dangerous situations
one example is when another program (not copyparty or its UI) wants to
rename a file from `Foo` to `foo`; the program will probably start by
checking if `foo` exists and then delete it, however this would match
`Foo` and confuse the program into deleting the wrong file
fix this by adding a VERY EXPENSIVE detector to prevent this,
by listing the parent folder and checking if the case matches
this check will auto-enable when a case-insensitive FS is detected on
startup, but option `casechk` (global or volflag) can override this
extends idp-auth to also accept a collection of headers (and
expected values of those headers) and map those to certain users
useful for Tailscale-User-Login and similar
togglebutton in the ui switches between 2 (off/default) and
1 (on/quick) confirmations; global-option `--qdel` sets the default
setting `--qdel=0` changes the togglebutton to switch
between 1 (off/default) confirmations and 0 (on)
in other words, when the ui-button is enabled, it
always reduces the number of confirmations by one
