No topic checking - and crash

[ckrey]

aedes allows using wildcards in PUBLISH:

• base/#
• base/+/sub

aedes allows using illegal wildcards in SUBSCRIBE and UNSUBSCRIBE:

• base/#/sub (multilevel wildcard not last element)
• base/#sub (wildcard not alone)
• base/+xyz/sub (wildcard not alone)

aedes does not check for empty (zero length) topics:

• in PUBLISH, aedes silently interrupts outgoing client connections (SUBSCRIBE to '#' in client A, send PUBLISH 'empty' from client B, connection to client A dies)
• in SUBSCRIBE aedes crashes

assert.js:60
  throw new errors.AssertionError({
  ^

AssertionError [ERR_ASSERTION]: '' == true
    at MQEmitter.on (/Users/ckrey/node_modules/mqemitter/mqemitter.js:74:3)
    at Aedes.subscribe (/Users/ckrey/node_modules/aedes/aedes.js:241:11)
    at SubscribeState.subTopic (/Users/ckrey/node_modules/aedes/lib/handlers/subscribe.js:106:12)
    at work (/Users/ckrey/node_modules/fastfall/fall.js:105:23)
    at /Users/ckrey/node_modules/aedes/lib/handlers/subscribe.js:74:5
    at MemoryPersistence.addSubscriptions (/Users/ckrey/node_modules/aedes-persistence/persistence.js:112:3)
    at SubscribeState.storeSubscriptions (/Users/ckrey/node_modules/aedes/lib/handlers/subscribe.js:73:9)
    at work (/Users/ckrey/node_modules/fastfall/fall.js:105:23)
    at Aedes.defaultAuthorizeSubscribe [as authorizeSubscribe] (/Users/ckrey/node_modules/aedes/aedes.js:306:3)
    at SubscribeState.authorize (/Users/ckrey/node_modules/aedes/lib/handlers/subscribe.js:39:17)