Fix rendering problems of Version 2.6.0

[de-jcup]

Situation

With Version 2.6.0 it is not possible to open /render Asciidoc files.
Always having the problem - sound similar to #412 which should be fixed by the changes in 2.6.0 but now it happens also on a Linux machine (but only in installed plugin, but not in runtime (developer) version) - strange...

Wanted

Fix the problem and have no installation of 2.6.0

Solution

• Changed marketplace setup back to 2.5.1 so users do not download/install 2.6.0
• Find the problem and fix it!

[de-jcup]

Analyse

• plain asciidoc files do work
• problems appear where a diagram (plantuml, ditaa etc.) is referenced. Those files cannot longer be found - reason: diagram path is wrong calculated!
• in general: the base path calculation is absolutely wrong, could be related to the changes made for Empty folder between asciidoc files prevents plantuml resolution #428
• Setting AsciiDoctorBaseDirectoryProvider.MAX_ACCPTED_EMPTY_FOLDERS to 0, does solve the problem

[de-jcup]

The solution is, to remove the implementation of #428 !