[librsvg: 1/2] Enable rustc lints and solve them

[Federico Mena Quintero <federico src gnome org>]

commit 5af037a1fe835564b3e0545a2f6ed8a397035d26
Author: Gabriel Majeri <gabriel majeri6 gmail com>
Date:   Mon Mar 30 20:02:31 2020 +0300

    Enable rustc lints and solve them
    
    # Conflicts:
    #       rsvg_internals/src/filters/error.rs

 librsvg_crate/src/lib.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
---
diff --git a/librsvg_crate/src/lib.rs b/librsvg_crate/src/lib.rs
index adeda5dc..8384a5c2 100644
--- a/librsvg_crate/src/lib.rs
+++ b/librsvg_crate/src/lib.rs
@@ -141,7 +141,14 @@
 //! [SVG 1.1]: https://www.w3.org/TR/SVG11/
 //! [SVG 2]: https://www.w3.org/TR/SVG2/
 
-#![warn(unused)]
+// Enable lint group collections
+#![warn(nonstandard_style, rust_2018_idioms, unused)]
+// Some lints no longer exist
+#![warn(renamed_and_removed_lints)]
+// Standalone lints
+#![warn(trivial_casts, trivial_numeric_casts)]
+#![warn(missing_docs)]
+#![deny(warnings)]
 
 use glib::prelude::*;
 use url::Url;