From the previous branch:
commit eda4928ff122a0845baf5ade83b4aa29244a3a89
Author: Olivier Bertrand <bertrandop@gmail.com>
Date:   Mon Mar 9 22:34:56 2015 +0100

- Add discovery to JSON tables
  When columns are not defined, CONNECT analyses the json file to find column definitions.
  This wors only on table that are an array of objects. Pair keys are used to generate the
  column names and pair values are used for its definition. When the LEVEL option is defined
  as a not null integer, the eventual JPATH is scanned up to the LEVEL value.

From the current one:
- Fix MDEV-7521 when column names are utf8 encoded (not a general multi-charset fix)

- Adds more to JSON discovery processing and UDF's

- Use PlugDup everywhere it replaces PlugSubAlloc + strcpy.