v0.6.19

ApproxFunBase v0.6.19

Diff since v0.6.18

Merged pull requests:

• fix nocat (#180) (@jishnub)
• store size for plus and times operators (#181) (@jishnub)
• copy vector in chop (#182) (@jishnub)
• bugfix in ldiv_coefficients (#183) (@jishnub)
• Fix similar for RaggedMatrix (#184) (@jishnub)
• domain promotion for cached operator (#186) (@jishnub)
• Fix indexing for PartialInverseOperator (#188) (@jishnub)
• triu/l for negative bandwidths (#189) (@jishnub)
• Add badges from Juliahub (#190) (@jishnub)
• Bump version to v0.6.19 (#192) (@jishnub)