Correct info about if/else syntax in configuration files. #4211 This
correction is in the 8.2.0 manual, although the original ticket is for
8.1.6.
define the new @include and @use syntax for configuration. Documentation
is in the 8.2.0 manual, even though the feature is in 8.1.6. #4319 #4031
Merge branch 'V8_2_0-branch' into V8_2-branch