Check mime type of picture instead of filename extension

[Aleksanaa]

For some reasons we may wish to set wallpapers with no filename extension (for example, I have a script to move wallpaper to ~/.local/share/background ) . However, swww refuses to use such files, throwing Error: "failed to open image '\"/home/aleksana/.local/share/background\"': The image format could not be determined".

In most cases on desktop linux, we do not determine file by its filename extension, but use mine types instead. You can use file --mime-type foo.bar to view a file's type.

[Aleksanaa]

The related code is in src/main.rs#L142, and the docs suggests .with_guessed_format(). I didn't make a pull request because I don't have a knowledge of writing rust at all. Please test it if possible.

[Aleksanaa]

Okay so I ended up writing this patch on my own (This is for 0.6.0, as master is unusable when I test it)

--- a/src/daemon/processor/mod.rs
+++ b/src/daemon/processor/mod.rs

@@ -138,7 +138,8 @@ impl Processor {
 
     pub fn process(&mut self, requests: Vec<ProcessorRequest>) -> Answer {
         for request in requests {
-            let img = match image::open(&request.path) {
+            let mut reader = image::io::Reader::open(&request.path).expect("idk").with_guessed_format().expect("The image format could not be determined");
+            let img = match reader.decode() {
                 Ok(i) => i.into_rgba8(),
                 Err(e) => {
                     return Answer::Err(format!(