simplify threadloop begin/end generation code
add test for continue in threadloop
allow use of the C continue statement at the top level of a threadloop
add vsearch_insert_leftmost, vsearch_insert_rightmost, vsearch_match, vsearch_bin_inclusive, vsearch_bin_exclusive and associated tests
code/doc generation of vsearch_* routines now table driven
don't use experimental lexical $_
test vsearch api to ensure backwards compatibility
vsearch() is now a front end to all vsearch_* routines

* old vsearch is now vsearch_sample
* clean up docs/code so signatures match documented arguments
add a test to see if at() and sclr() both return BAD values

The current issue is that `at` will return the Perl string BAD, but
`sclr` does not. This causes issues with other functions that use `sclr`
such as `minmax`.
check that stringify is overloaded

This currently fails as mentioned in <https://sourceforge.net/p/pdl/bugs/356/>.
The reason is that the overload method is `PDL::Core::string` which is
aliased to `PDL::string`. The issue is that the alias does not exist
when the overload is applied.
testing `min` and `max` behaviour with BAD values

Problems with this behaviour were brought up at
<http://mailman.jach.hawaii.edu/pipermail/pdl-porters/2014-November/006437.html>.
put the aliases in a BEGIN block so that are defined early

This fixes an issue that came up with `overload::Method()` not knowing
where `PDL::Core::string` was defined as described here
<https://sourceforge.net/p/pdl/bugs/356/>.
Merge commit '6c1737f799a18de9715d14c42f2b8d82a4154bf4'
Merge commit 'df8b4287b9f53cc71792cde3d7b5f70abeb3c704'
Add test labels to new at() and sclr() bad checks
Make new at/sclr bad test a TODO
Merge commit 'cefc1b7ebf909039a98ac684c27763193ead0e21'
Make tests TODO and add comment re perl scalar vs pdl values for BAD
Merge commit 'ec6f92be4cf311e5725481dd109c6d96d96549a4'
add better comments and test names to t/minmax-behavior.t

The problem has to do with the difference between return values
that are perl scalars versus those that are pdls.  This is still
an issue to resolve but may be more undocumented that a bug.
More consistency would be nice to add...