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/envparams.rs

@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: LGPL-2.1
+// Copyright 2021 Daniel Vogelbacher <daniel@chaospixel.com>
+
+use log::warn;
+
+pub(crate) fn rawler_ignore_previews() -> bool {
+  match std::env::var("RAWLER_IGNORE_PREVIEWS").map(|val| val.parse::<u32>()) {
+    Ok(Ok(value)) => value == 1,
+    Ok(Err(_)) => {
+      warn!("Invalid value for RAWLER_IGNORE_PREVIEWS");
+      false
+    }
+    Err(_) => false,
+  }
+}
+
+pub(crate) fn rawler_crx_raw_trak() -> Option<usize> {
+  match std::env::var("RAWLER_CRX_RAW_TRAK").map(|val| val.parse::<usize>()) {
+    Ok(Ok(value)) => Some(value),
+    Ok(Err(_)) => {
+      warn!("Invalid value for RAWLER_CRX_RAW_TRAK");
+      None
+    }
+    Err(_) => None,
+  }
+}
+
+pub(crate) fn rawler_dng_rows_per_strip() -> Option<usize> {
+  match std::env::var("RAWLER_DNG_ROWS_PER_STRIP").map(|val| val.parse::<usize>()) {
+    Ok(Ok(value)) => Some(value),
+    Ok(Err(_)) => {
+      warn!("Invalid value for RAWLER_DNG_ROWS_PER_STRIP");
+      None
+    }
+    Err(_) => None,
+  }
+}
+
+pub(crate) fn rawler_dng_multistrip_threshold() -> Option<usize> {
+  match std::env::var("RAWLER_DNG_MULTISTRIP_THRESHOLD").map(|val| val.parse::<usize>()) {
+    Ok(Ok(value)) => Some(value),
+    Ok(Err(_)) => {
+      warn!("Invalid value for RAWLER_DNG_MULTISTRIP_THRESHOLD");
+      None
+    }
+    Err(_) => None,
+  }
+}