* added parser for durations
* preliminary work for timeframes
* Update CMakeLists.txt
* updated parsing and generation for durations
* renames
* report parser errors; added compatibility to existing config_parse_duration()
* duration parsing is used on most netdata.conf and stream.conf entries
* more uses of duration parsing; simplification of stream.conf
* code cleanup
* more duration changes
* added html playground
* improved js code
* duration parsing applied to dbengine retention
* fixed doc
* simplified logic; added size parser
* added parsing for sizes
* renames and documentation updates
* hide appconfig internals from the rest of netdata
* fix crash on cleanup of streaming receivers
* fix buffer overflow in gorilla compression
* config return values are const
* ksm set to auto
* support reformatting migrated values
* removed obsolete metrics correlations settings
* split appconfig to multiple files
* durations documentation
* sizes documentation
* added backward compatibility in retention configuration
* provide description on migrations and reformattings
* config options are now a double linked list
* config sections are now a double linked list; config uses spinlocks; code cleanup and renames
* added data type to all config options
* update data types
* split appconfig api to multiple files
* code cleanup and renames
* removed size units above PiB
* Revert "fix buffer overflow in gorilla compression"
This reverts commit 3d5c48e84b.
* appconfig internal api changes
