Added contextual signature instantiation during type inference.
Fixes #88.
Complain when a non-void/any function lacks a return expresson.

In effect this fixes #62.

Also
    - Changes the error message for get accessors lacking return expressions.
    - Actually checks for return expressions instead of return statements for get-accessors.
    - Removes fancy quotes.
    - Corrects errors in the compiler caught by the new check.
    - Simplified `checkAndAggregateReturnTypes` by extracting it out to `visitReturnStatements`.
Removed TODO relating to the task I just fixed.
Minor renaming.
Changed check on annotated functions/getters to only look for return statements.
Changed error message for annotated functions lacking return statements.
Add node_modules\.bin to path.
Fixes browserify task when browserify isn't installed globally.
Fixed misleading comment

As per Cyrus's comment in #173.
Merge pull request #180 from DickvdBrink/no-global-modules

Fixes browserify task when browserify isn't installed globally.
Addressing CR feedback.
Adding comment to explain source type instantiation.
Adding a test case.
Merge pull request #175 from Microsoft/contextualSignatureInstantiation

Added contextual signature instantiation during type inference.
Aligning index signature type inference with assignability rules.
Type inference now supports inferring from string index signatures to numeric index signatures.
Fixes #167.
Merge pull request #196 from Microsoft/indexSignatureTypeInference

Aligning index signature type inference with assignability rules.
Initial work to enable Travis-CI support
Merge pull request #147 from Microsoft/noReturnExpression

Complain when a non-void function lacks a return expresson.
Removed parentheses around arrow function parameters.

As per feedback in pull request #147.
Merge branch 'master' into errorOnWithStatement