v0.15.0

ManifoldsBase v0.15.0

Diff since v0.14.12

Merged pull requests:

• Unify exp and retract, log and inverse_retract (#167) (@kellertuer)
• Define Meta Manifolds already in ManifoldsBase (#169) (@kellertuer)
• Unify error= keyword (#170) (@kellertuer)

Closed issues:

• Change function signature of is_ functions to be consistent with isapprox. (#135)
• Unify exp and retract (#159)