v0.8.0

DataFramesMeta v0.8.0

Diff since v0.7.1

Merged pull requests:

• Re-factor macro-flag handling, fix Table-returning paths, only allow DataFrames 0.22 and above (#261) (@pdeffebach)
• Deprecate @linq in favor of re-exporting @chain. (#262) (@pdeffebach)
• Add @subset (#263) (@pdeffebach)
• :y = f(:x) instead of y = f(:x) (#264) (@pdeffebach)
• Bump version to 0.8.0 (#268) (@pdeffebach)