Intellij D Language plugin v1.28.1

[singingbush]

Following on from the 1.28.0 release earlier this month. A bunch 
of issues have been resolved 
https://github.com/intellij-dlanguage/intellij-dlanguage/milestone/33?closed=1 and a new release has been published to the Jetbrains plugin repository: https://plugins.jetbrains.com/plugin/8115

The documentation (here https://intellij-dlanguage.github.io and 
https://github.com/intellij-dlanguage/intellij-dlanguage/wiki) 
still needs updating.

As always, there's much to do 
(https://github.com/intellij-dlanguage/intellij-dlanguage/issues). Help with testing, documentation, detailed bug reports, and pull requests for features/bugfixes is welcome.