Smack 4.0.3-SNAPSHOT
Fix FormField.Option.toXML() to use correct element

Fixes SMACK-589
Improve documentation (targetCompatibility, XPP3)
Fix Typo: s/isSubscibe/isSubscribe/ in ConfigureForm

Fixes SMACK-588
Verify ConnectionConfiguration parameters

also fix javadoc error for StringUtils.isNullOrEmpty()

Fixes SMACK-539
Make getMessages() set up collector *before* sending the request

Similar flaw was also fixed in 2c7f1efe80b988.

Also ensure that OfflineMessagesManager doesn't leak collector by using
a try/finally block.

Fixes SMACK-592
Make Socks5Proxy try other ports if 7777 is already in use

by setting the default value to '-7777' (negative values mean that the
next port number will be tried if the current one is in use).
Throw IAE if invalid port number is given for Socks5Proxy
Add a setting for the used flush mode when compressing data

Fixes SMACK-593
Merge branch '4.0'

Also slightly improve OfflineMessageManager.getMessages()

Conflicts:
	build.gradle
	smack-extensions/src/main/java/org/jivesoftware/smackx/offline/OfflineMessageManager.java
Check if android.jar exists

and throw exception if not