Add an API for multi-key index extractors.
Typo, edit the template, not the generated file.
Update Python and Java APIs for WT_EXTRACTOR_MULTIPLE.
Merge branch 'develop' into custom-extractors
Add example of how to use custom extractor.
Add more to extractor example.
Flesh out extractor example program.
Simplify the custom extractor API so that:

1. it makes direct calls to WT_CURSOR::insert, addressing issues with memory management; and
2. it can repeat this multiple times synchronously rather than needing an additional interface for multiple keys.

Fill in some more of the implementation.
Typo
Merge branch 'develop' into custom-extractors

Conflicts:
	examples/c/ex_all.c
	src/include/wiredtiger.in
Fix bug setting extractor key to year.  Add debug and remove support.
Remove wt_extractor_multiple from language files.
Remove extractor_multiple from docs file.
More implementation of the custom extractor API.  Still working on generating plans and key formats between index creation and open.

refs #1199
More implementation of custom extractors: pass the number of columns calculated by index creation through to the open, use that to generate correct key formats and a plan that can extract the primary key.
Merge branch 'develop' into custom-extractors
Clarify the requirements for named columns and key formats with custom extractors.

refs #1199
Don't use const for strings returned in allocated memory.
Strip metadata from JSON dumps if if cannot be passed to WT_SESSION::create.
Handle custom extractors where the last key column is a WT_ITEM.

refs #1199