[show-hint addon] Be more precise in identifying hint element

... to prevent misbehavior in cases where the rendered hint element
contains an LI in its child nodes
[searchcursor addon] Deal with characters that multiply on case folding

And add a test suite.

Issue #2009
[activeline addon] Optimize

Issue #2007
Add an (experimental) hideFirstChars method to StringStream

Issue #2019
Disable a search test on Phantom

Due to unexplainable hanging.
Replace accidental emdash with dash in regexp
Merge branch 'master' of https://github.com/marijnh/CodeMirror