Added getOccs support for if/else keywords, and some tests.
Addressed CR feedback, no longer highlighting elseifs with comments between.
Added test case for broken if-elses.
Added missing break statement.
Use isWhitespace in getIfElseOccurrences.
Merge pull request #561 from Microsoft/getOccurrencesIfElseIfElseIfElse

getOccurrencesAtPosition support for if/else keywords