Add options for adaptive compression

The adaptive compression is a system that allows you to download less data if you're willing to sacrifice some quality. You can set a target compression ratio or tolerance and the system will choose the adaptive level that best matches your target (there are a discrete number of quality levels stored when the data is compressed). In particular, compressing the data with the WaveletLossless method is only really useful if you want to export a bit-equivalent dataset to the original, you're always better off reading with an adaptive tolerance of 0 which gives you nearly lossless data at a much better bitrate. This resolves #64 (closed) "Add options for adaptive streaming".