Improve deflate support

- Switch to streaming decompression via `flate2`. Aside from performance improvements and lower RAM consumption, this fixes a bug where `max_uncompressed_length` was precalculated for a single tile but then used as a hard limit on the whole data, failing to decompress any tiled images.
 - Deprecate `InflateError` - this was used for wrapping `miniz_oxide` raw status, but `flate2` already reports them as `io::Error` instead. This makes errors from both Lzw and Deflate modes more consistent - they're all now just `io::Error`.
 - Add support for new `Deflate` tag in addition to `OldDeflate` - format-wise it's same Zlib, and on practice decodes successfully with the same underlying code.
 - Slightly simplify partial reads from the `Reader` by using the `std::io::copy` helper instead of doing it manually.

Fixes #131.

Cargo.toml

@@ -20,10 +20,7 @@ edition = "2018"
 [dependencies]
 weezl = "0.1.0"
 jpeg = { package = "jpeg-decoder", version = "0.1.17", default-features = false }
-
-[dependencies.miniz_oxide]
-version = "0.4.1"
-features = ["no_extern_crate_alloc"]
+flate2 = "1.0.20"
 
 [dev-dependencies]
 criterion = "0.3.1"