Release 0.15.0

What's Changed

• Load command by @pkolaczk in #20
• More Rune functions by @pkolaczk in #22
• Generating textual data by @pkolaczk in #23
• Common code in lib.rn by @pkolaczk in #24
• Add optional custom tags in hdr output by @pkolaczk in #25

Full Changelog: v0.14.0...v0.15.0