Vendor rawler 0.7.2 unmodified

The crate as crates.io publishes it, minus .cargo-ok, its Cargo.lock and
data/testdata (13 MB of sample files only its own tests read). Not yet
routed through [patch.crates-io]; the next commit is the patch.

third_party/rawler-0.7.2/src/buffer.rs

@@ -0,0 +1,51 @@
+use std::ops::Deref;
+
+/// Buffer to hold an image in memory with enough extra space at the end for speed optimizations
+pub struct PaddedBuf<'a> {
+  buf: PaddedBufImpl<'a>,
+  size: usize,
+}
+
+pub enum PaddedBufImpl<'a> {
+  Owned(Vec<u8>),
+  Ref(&'a [u8]),
+}
+
+impl<'a> PaddedBuf<'a> {
+  pub fn new_owned(buf: Vec<u8>, size: usize) -> Self {
+    Self {
+      buf: PaddedBufImpl::Owned(buf),
+      size,
+    }
+  }
+
+  pub fn new_ref(buf: &'a [u8], size: usize) -> Self {
+    Self {
+      buf: PaddedBufImpl::Ref(buf),
+      size,
+    }
+  }
+
+  pub fn size(&self) -> usize {
+    self.size
+  }
+
+  pub fn buf(&'a self) -> &'a [u8] {
+    self
+  }
+
+  pub fn real_size(&self) -> usize {
+    self.buf().len()
+  }
+}
+
+impl<'a> Deref for PaddedBuf<'a> {
+  type Target = [u8];
+
+  fn deref(&self) -> &Self::Target {
+    match &self.buf {
+      PaddedBufImpl::Owned(x) => x.as_ref(),
+      PaddedBufImpl::Ref(x) => x,
+    }
+  }
+}