[Format] Struct type name consistency in implementations and metadata

[toddfarmer]

Note: This issue was originally created as ARROW-278. Please see the migration documentation for further details.

Original Issue Description:

As discussed in apache/arrow#121 for ARROW-262, the Struct name is reserved in Flatbuffers, so we temporarily used the Tuple name. We should either use a tweaked name like Struct_ that does not cause conflicts or choose a name for the Struct concept (e.g. Tuple) and use that consistently in format documents and implementation.

The least disruptive solution is to use the Struct_ name in the Flatbuffers IDL.

Migrated issue participants:

Reporter: Wes McKinney (wesm)
Assignee: Wes McKinney (wesm)

[toddfarmer]

Note: Comment by Julien Le Dem (julienledem):
"Struct_" works for me.
I tried with "Struct", the parser does not fail but the java classes generated do not compile since Struct is also the name of the base class and the names conflict.

[toddfarmer]

Note: Comment by Wes McKinney (wesm):
Fine by me. I think "Struct" may only be reserved in C++

[toddfarmer]

Note: Comment by Wes McKinney (wesm):
See apache/arrow#130

[toddfarmer]

Note: Comment by Julien Le Dem (julienledem):
Issue resolved by pull request 130
apache/arrow#130