This should help answer questions such as #605 in the future

* fixed for simpler parenthesis matching

* absolute file path for .fehbg, moved script creation into helper function

* Removed unused variable.

* added early exit condition as per Ferada's suggestion

* Added enum for options to improve readability

* migrated options to enum.

* added support for zoom specification through options

* added man entry for zoom-rate

* added help entry for zoom-rate commands

* updated man to have warnings about strange values for zoom options

* fix memory leak (free exec_absolute_path)

* added detection for path vs env PATH launch for use in .fehbg script gen.

* Added enum for options to improve readability

* migrated options to enum.

* added support for zoom specification through options

* added man entry for zoom-rate

* added help entry for zoom-rate commands

* updated man to have warnings about strange values for zoom options

* Update help.raw

removed zoom-in/out

* removed zoom-in/out from options

* updated man/help entry to remove in/out zoom specification

* sanitize --zoom-rate in options parser; use a single variable for storing it

Co-authored-by: Daniel Friesel <derf@finalrewind.org>

Closes #583

Closes #577

This works around a regression in Imlib2, which makes (un)loadable file
detection quite slow when handling e.g. large video files. See
<https://phab.enlightenment.org/T8739> and
<https://github.com/derf/feh/issues/505> for details.

Closes #505

feh.1:588:33: WARNING: new sentence, new line

Closes #545

This lets `feh` draw the background pixmap of an existing window,
opening the door for use with tools like `xscreensaver` or `xsecurelock`

The --version-sort option requires strverscmp(), but this is a glibc
extension that does not exist on OpenBSD and other systems. To enable
--version-sort on those systems, provide an internal implementation of
strverscmp(). The implementation is from the musl C library and is
MIT-licensed.

The build process remains the same: the verscmp flag should be set to 1
only if strverscmp() is available in libc. If verscmp is 0, then the
internal implementation is used.

It's called conversion-cache for now, as it will also be used for
ImageMagick/dcraw-sourced images in the future. This should also help
avoid confusion between HTTP/ImageMagick/dcraw cache (files on disk),
Imlib2 cache (images in memory), and thumbnail cache.

Closes #506

This ensures that X11 layout or other changes do not affect the .fehbg
contents, which are meant to only be updated when a --bg-option is used
manually.

Closes #482

Small fixes in man page.

This changes the behaviour of "feh --start-at FILENAME" as follows:

Previously, this would cause feh to load all files in the current
working directory, since no files or filelists were specified on the command
line.

Now this is a special case: feh will extract the directory component from
FILENAME, load all files in that directory, and display FILENAME.
This way, it's possible to use "feh --start-at ~%f" in XDG Desktop files
and browse files in feh using the prev/next keys

Closes #372
Closes #420

This more closely resembles the expected behaviour of --start-at, but
may lead to mismatches if several files in the filelist have the same
basename.

Closes #206

Related to #372 and #420

This is in line with other software. save_filelist now defaults to "L".