Refactoring: move ui.editors.AnalyzerScheduler.java to core.resolve.AnalyzerScheduler.java

Refactoring: move ui.editors.AnalyzerSchedulingRule.java to core.resolve.AnalyzerSchedulingRule.java
After analyzing project return more common BindingContext class, not only Diagnostics
Register JavaFileManager service to get all descriptors from resolution scope
Add basic completion
Complete identifier with keyword and if there is no space before it
Refactoring: rename package tests.completion.templates to tests.editors.completion.templates
Refactoring: move method getCaret() to its super class
Add testframework for completion
Add tests for completion
Strange commit about loadFileText
Move getImage for descriptor to applicable class
Minor: add NotNull annotation to method
Minor: remove useless check
Minor: extract variable
To get presentable string for descriptor use DescriptorRenerer