fixing NullPointerException in settings processing

• fixing NullPointerException in settings processing (#266)
• supporting pass-through inline content

Breadcrumbs, Update asciidoctorj-diagram

• update to asciidoctorj-diagram:1.5.18
• breadcrumb support in editor

Tuning language injection

• supporting blanks in block attributes (#255)

Language injection and Statement Completion

• adding support for GRAPHVIZ_DOT environment variable (#261)
• adding support for statement completion (ctrl-shift-enter) (#263)
• language injection can now is now enabled by default and can be disabled for specific languages, and will be disabled when the block has an include::[] (#255)
• includes are now parsed and highlighted inside code blocks (#255)

Experimental highlighting in code blocks

• Experimental highlighting in code blocks (#255, #262)

Highlighting for link:file[] and attribute values and references

• upgrading gradle and JetBrains plugin; now use gradlew runIde to start the plugin in development mode
• allow user to switch left/right and upper/lower in split view (#136)
• add syntax highlighter to support link:file[] (#259)
• add syntax highlighter to support attribute:value and {attribute reference} (#260)

Default JRuby encoding to UTF-8 if local encoding is not supported by JRuby

• default file encoding for JRuby now UTF-8 if set file encoding is not supported by JRuby (#174)

fixing error in tree structure, improved test capabilities

• fixing error in tree structure; improving test capabilities for parsing (#174)

Brace matcher and folding improvements

• improved brace matcher
• ensure that block IDs are part of next section when folding (#174)

Tuning link navigation in preview

• decouple read action from event thread to avoid error from IDE (#204)
• highlighting for lexical quotes
• parsing referenced file from reference (#204)