Fix nested values can span sections (go-ini#306)

Fix python multiline EOF error (go-ini#309)

file: add `HasSection` method (go-ini#308)

Co-authored-by: Joe Chen <jc@unknwon.io>

Fix parsing python multiline string (go-ini#299)

file: fix legacy tests

test: rename package to be same as the main (go-ini#304)

ci: workaround to make lint work (go-ini#303)

key: add `AllowDuplicateShadowValues` option (go-ini#298)

section: preallocate the size of keys hash (go-ini#297)

Add extends functionality to allow embedded fields (go-ini#269)

* Add extends functionality to allow embedded fields

Signed-off-by: Andrew Thornton <art27@cantab.net>

* allow extends with name

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Update struct.go

Co-authored-by: ᴜɴᴋɴᴡᴏɴ <u@gogs.io>

* Update struct_test.go

Co-authored-by: ᴜɴᴋɴᴡᴏɴ <u@gogs.io>