[pdal] Standardize on Boost 1.42+

[Howard Butler]

Michael,

Here's my failures on linux with boost 1.42:

/home/oracle/pdal/test/unit/pcinfoTest.cpp(159): error in "pcinfo_test_dumps": check Support::compare_text_files(outputTxt, Support::datapath("apps/pcinfo_schema.txt")) failed
/home/oracle/pdal/test/unit/pcinfoTest.cpp(165): error in "pcinfo_test_dumps": check Support::compare_text_files(outputTxt, Support::datapath("apps/pcinfo_stage.txt")) failed

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and on OSX with boost 1.47:

/Users/hobu/dev/git/pdal/test/unit/pcinfoTest.cpp:165: error in "pcinfo_test_dumps": check Support::compare_text_files(outputTxt, Support::datapath("apps/pcinfo_stage.txt")) failed

Support::compare_text_files in test suite not that instructive. Maybe these could be string comparisons with BOOST_CHECK_EQUAL?  I'm not quite sure what to do, as I can see you wouldn't want to barf 1000s of characters onto the console that doesn't tell you much about what's not equal anyway.

I would like to standardize on boost 1.42+ as our Boost requirement for PDAL.  If we really need something that is newer than that, we should copy it into our own namespace and plop it in #include <pdal/external/boost_something>.  Otherwise, we should do our best to get back to 1.42.  

Why 1.42?  That's what's available from package for Debian Squeeze and Ubuntu Natty Narwhal, which are popular "cutting edge"  Linux distros. Stabilizing on this version gets us much easier access to being in the DebianGIS packaging effort, which services both of these distributions.  It will make it easier to get solicit packaging help. Also, using an older boost won't raise up developer's hackles when they first embark on trying to get going with PDAL.

Howard