Section::getSection: accept name or id

Part of issue #354
Merge pull request #418 from gicmo/section_by_name

Section::getSection: accept name or id
File API name/ID cleaning issue #354
Section API name/ID cleaning issue #354
File API - corrections to the front #354
Merge pull request #420 from asobolev/master

File API name/ID cleaning issue #354

LGTM
Block.source API name/ID cleanup
Block.dataarray API name/ID cleanup
Block.multitag API name/ID cleanup
Merge branch 'dev'
Merge pull request #421 from asobolev/master

Block / Section API name/ID cleanup