v1.7 - Lightweight database & harmonized gene symbols

This is the seventh minor release (v1.7) introducing a lightweight database version, various gene symbol improvements, and a metagenome mode.

Compatible database scheme version: 5

New features:

• Introduced a lightweight database version: #196 (Thanks @tseemann))
• Introduced an operon gene symbol harmonization feature: #190
• Introduced a simple metagenome mode: #191
• Added IS transposase to protein expert system: #10

Improvements:

• Improved CDS gene symbols: #186
• Amended tRNA & rRNA gene symbols: #192
• Amended uppercase ncRNA gene symbols: #194
• Added model IDs and dbxrefs to expert annotation systems: #183 (Thanks @davidtong28)
• Updated to Pyrodigal v2.1.0 fixing a bug in the SD motif-detection on reverse contig edges: 599fe70

Fixes:

• Fixed system-wide db path stored in software volume: #177 (Thanks @standage)