ZPAQ Block Sizes can be independently set

[pete4abw]

Starting with release 0.8.8, a new feature is available.
lrzip-next -z --zpaqbs=## where ## is between 1 and 11. Memory permitting, these block sizes may improve compression ratios, but will definitely increase compression time.

ZPAQ 7.15 block sizes are defined as 2^BS * 1MB, and the default block size is 2^4 * 1MB or 16MB
lrzip-next assigns block sizes based on compression level. This new option will permit the higher block sizes.

ZPAQ Block #	ZPAQ Block Size	lrzip-next Comp Level	ZPAQ Comp Level	ZPAQ Block #
1	2,097,192	1	3	4
2	4,194,304	2	3	4
3	8,388,608	3	3	4
4	16,777,216	4	4	5
5	33,554,432	5	4	5
6	67,108,864	6	4	6
7	134,217,728	7	4	7
8	268,435,456	8	4	8
9	536,870,912	9	5	9
10	1,073,741,824	N/A	N/A	N/A
11	2,147,483,648	N/A	N/A	N/A