beta - Update to AMR++ v4 with single-end and merged-read analysis.

Detailed changes here.

Brief overview:
1.Added single-end and merged-read analysis.
2. Switch to only counting primary resistome alignments.
3. Changed default AMR gene fraction --threshold to 0. We recommend running statistical analysis of count matrices after aggregating to the "Group" level to account for possible false-positive calls of individual gene accessions.
4. Changed defaults to skip rarefaction analysis, but default to running the SNP confirmation and deduplication of resistome counts.
5. Added more tutorials, FAQs, and other documentation.