Starting on writing the library

Currently just parses the superblock (but that works!)

compressionoptions.go

@@ -0,0 +1,45 @@
+package squashfs
+
+//CompressionOptions
+type CompressionOptions interface {
+	Decompress([]byte) []byte
+}
+
+//TODO: Allow creation of options for compression.
+
+type gzipOptionsRaw struct {
+	compressionLevel int32
+	windowSize       int16
+	strategies       int16
+}
+
+//GzipOptions is the options used for gzip compression. Backed by the raw format, with strategies parsed.
+type GzipOptions struct {
+	CompressionOptions
+	raw                      *gzipOptionsRaw
+	DefaultStrategy          bool
+	FilteredStrategy         bool
+	HuffmanOnlyStrategy      bool
+	RunLengthEncodedStrategy bool
+	FixedStretegy            bool
+}
+
+type xzOptionsRaw struct {
+	dictionarySize    int32
+	executableFilters int32
+}
+
+type lz4OptionsRaw struct {
+	version int32
+	flags   int32
+}
+
+//ZstdOptions is the options set for zstdOptions
+type ZstdOptions struct {
+	CompressionLevel int32 //CompressionLevel should be between 1 and 22
+}
+
+type lzoOptionsRaw struct {
+	algorithm        int32
+	compressionLevel int32
+}