Tidy up and fix warnings

src/context.rs

@@ -1,9 +1,7 @@
 use parking_lot::ReentrantMutex;
-use std::cell::RefCell;
 use std::ffi::CStr;
 use std::ops::Drop;
 use std::ptr;
-use std::rc::Rc;
 
 use crate::io::Io;
 use crate::string::{ImStr, ImString};

src/image.rs

@@ -1,4 +1,3 @@
-use std::collections::HashMap;
 use std::marker::PhantomData;
 use std::os::raw::c_void;
 
@@ -185,38 +184,3 @@ impl<'ui> ImageButton<'ui> {
         }
     }
 }
-
-/// Generic texture mapping for use by renderers.
-#[derive(Debug, Default)]
-pub struct Textures<T> {
-    textures: HashMap<usize, T>,
-    next: usize,
-}
-
-impl<T> Textures<T> {
-    pub fn new() -> Self {
-        Textures {
-            textures: HashMap::new(),
-            next: 0,
-        }
-    }
-
-    pub fn insert(&mut self, texture: T) -> TextureId {
-        let id = self.next;
-        self.textures.insert(id, texture);
-        self.next += 1;
-        TextureId::from(id)
-    }
-
-    pub fn replace(&mut self, id: TextureId, texture: T) -> Option<T> {
-        self.textures.insert(id.id(), texture)
-    }
-
-    pub fn remove(&mut self, id: TextureId) -> Option<T> {
-        self.textures.remove(&id.id())
-    }
-
-    pub fn get(&self, id: TextureId) -> Option<&T> {
-        self.textures.get(&id.id())
-    }
-}

src/render/draw_data.rs

@@ -1,4 +1,3 @@
-use std::mem;
 use std::slice;
 
 use crate::internal::{RawCast, RawWrapper};