provide file completions in '[...](|)' for markdown documents
refactor 'cursor-mode' functions into own class
resolve filepath code with new lookup behaviour
missing '!'
fix indentation
move mode check later (allow completion narrowing in markdown mode)
disable completions in most contexts for markdown / tex
Merge pull request #224 from rstudio/feature/r-markdown-link-completions

provide file completions in '[...](|)' for markdown documents
Merge branch 'master' into feature/r-completion-signature-tooltip

Conflicts:
	src/gwt/src/org/rstudio/studio/client/workbench/views/console/shell/assist/RCompletionManager.java
remove old code