#2 External editor - Ability to declare package name explicitly

[leekang]

Some editors use fully qualified name for activity name and it "can" be different from package name.
(For example 'Jota Plus' uses 'jp.sblo.pandora.jotaplus.Main' for main activity while its package name is 'jp.sblo.pandora.jota.plus' )

This patch assumes any strings before 'slash' as explicit package name.
Additionally, activity name which has one or more dots can be accepted.

so user can set external editor in 3 ways:
1.. Fully Qualified Name without package (Current behaviour)
com.my.package.activity

2.. Fully Qualified Name
com.my.package/com.my.package.activity.name
com.my.package/com.other.package.activity

3.. relative class name
com.my.package/.activity
com.my.package/.activity.name