Split the data type detection from the actual data type conversion in
the ConfigKey::parse_string() method. Allow the Option class to re-use
the public ConfigKey method, to share the maximum amount of data type
conversion code for both Driver and InputFormat option specs.
This is the least intrusive yet most reliable and consistent approach in
the libsigrok C++ binding that allows applications to support driver scan
and input file format options from command line arguments.
Since Autoconf places some important feature flags only into the
configuration header, it is necessary to include it globally to
guarantee a consistent build.
The tables defined with this struct can now be used for information
on items other than config keys.
Functions to access these tables have been renamed sr_key_info_[name_]get.
These take an extra argument, keytype, which should be set to SR_KEY_CONFIG
to get the config key tables. Other key types will be added.