Add optional Pareto distribution random numbers to wtperf.
Fix a comment.
Merge branch 'develop' into data-source
wtperf requires the math library, add a link.
Merge branch 'develop' into data-source
First cut at moving the configuration information into the WT_CONNECTION_IMPL
structure: create the array of WT_CONFIG_ENTRY structures that the connection
references, and a set of #defines so we can easily reference any single slot.

Replace API_CONF_DEFAULTS and explicit references to the old structures with
WT_CONFIG_VALUE and WT_CONFIG_CHECKS.

Some (hopefully) minor shuffling of the cfg array manipulation in various
chunks of code.  The test suite and various test programs run with this
change.