Add a cursor operation to skip the in-order key check in a row-store,
configure it from LSM.

Explode the bulk cursor insert routines into a routine per btree type.

Reference #1127.
Put the general-purpose smoke-test of bulk load first, fix a comment.
When splitting out the variable-length column-store bulk-load function,
I broke it, inserting a non-existent record, the salvage test caught it.
Once the methods are broken apart, there's no reason to test
WT_BC_SKIP_SORT_CHECK here.
If we're not comparing against the next key, there's no reason to save
a copy of the current bulk key.
Delete the bulk cursor's WT_BC_SKIP_SORT_CHECK flag, it's not needed.
In function '__wt_bulk_insert_row_skip_check':
error: variable 'cursor' set but not used [-Werror=unused-but-set-variable]
Merge the mid-level of the bulk code into the cursor level.
unused variables ref, page
Merge pull request #1138 from wiredtiger/skip-bulk-sort-check-merge

Merge the mid-level of the bulk code into the cursor level.
Make comment logic match the code (zero/non-zero).
Merge pull request #1135 from wiredtiger/skip-bulk-sort-check

Add a cursor configuration to skip the in-order key check in a row-store bulk load.