v3.1.3

• Fixing compatibility with older browsers (@haroldhues).

v3.1.2

• Fixing #.once related bug (@iaspin92).

v3.1.1

• Dropping non-breaking spaces in code.
• Fixing object polymorphisms for ES6 symbols.

v3.1.0

• Adding ES6 Symbols support.

v3.0.1

• Fixing Emitter.once edge case.
• Fixing Emitter.kill edge case.

v3.0.0

Dropping useless Function.call occurrences