Fixed handling multiple occurences of a variable

Add some extra type checks on names (vlucas#351)

Fixed detection of closing multiline-quotes (vlucas#342)

Fixed parsing regressions (vlucas#339)

Fixed parsing regressions (vlucas#338)

Merge pull request vlucas#325 from vlucas/parser-backport

[2.6] Backport parser fixes from 3.3.0

Rewrite parser and fix escaped quotes in multiline values (vlucas#322)

Merge pull request vlucas#321 from GrahamCampbell/direct-load

Support direct loading with a string

Allow DotenvFactory to accept an empty array of adapters (vlucas#320)

Apply fixes from StyleCI (vlucas#317)