Add daemon mode support

Cargo.lock

@@ -1072,6 +1072,7 @@ version = "0.1.0"
 dependencies = [
  "dirs",
  "env_logger",
+ "fork",
  "gstreamer-tag",
  "i18n-embed",
  "i18n-embed-fl",
@@ -1765,6 +1766,15 @@ version = "0.3.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "aa9a19cbb55df58761df49b23516a86d432839add4af60fc256da840f66ed35b"
 
+[[package]]
+name = "fork"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05dc8b302e04a1c27f4fe694439ef0f29779ca4edc205b7b58f00db04e29656d"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "form_urlencoded"
 version = "1.2.1"