Syntax coloring should be on by default

Fix #202
Merge pull request #206 from dungpa/disabling-option

Syntax coloring should be on by default
improve symbol visual range recognition
rename several symbols

add an ignored SourceCodeClassifier test for Async type
Updated to FsXaml 0.9.3

Fixes Issue #190
Merge pull request #209 from ReedCopsey/master

Updated to FsXaml 0.9.3
Merge pull request #207 from vasily-kirichenko/improve-color-categories-detection

Improve symbol visual range recognition