Move classes from cache package to io package.

src/main/java/cz/it4i/qcmp/DataCompressor.java

src/main/java/cz/it4i/qcmp/benchmark/SQBenchmark.java

...main/java/cz/it4i/qcmp/compression/SQImageCompressor.java

...main/java/cz/it4i/qcmp/compression/VQImageCompressor.java

src/main/java/cz/it4i/qcmp/fileformat/SqQvcFile.java

src/main/java/cz/it4i/qcmp/fileformat/VqQvcFile.java

src/main/java/cz/it4i/qcmp/io/QuantizationCacheManager.java

src/main/java/cz/it4i/qcmp/io/QvcFileReader.java

src/main/java/cz/it4i/qcmp/io/QvcFileWriter.java