[Plug-in API] Make all ranges zero based

[mmorhun]

For now we have 0-based and 1-based ranges in our plugin API implementation. Taking into account, that end user should use 0-based ranges we have to use the same inside our implementation and convert to 1-based only before passing to monaco editor (or before transfer via rpc, but it should be only one place).
Also this should include fix for existing API's.

[mmorhun]

toRange and fromRange in type-converters.ts aren't consistent. fromRange makes only columns 1-based and leaves line numbers as is (which is wrong).

[mmorhun]

Done.
Old plugins which use wrong indexing might work incorrectly now. All editor related indexes inside any plugin must be zero based (see docs).