Revert "Enable gesture typing - (1/3) -LatinIME part"

This reverts commit ef94d9f7fcdbce96ed42fe6494c34139af754223.
LatinIME: Add @ character to DE keyboard's more keys

Change-Id: I6a85496e579170a67352160277bfb43125b1e892
Fix LatinIME crashing if JNI lib without gesture support is installed.

Change-Id: I60292a8e272d484e1d4a4407ddceeac863d6d70e
LatinIME: Add fallback loader for JNI lib

Prefer the JNI lib with gesture typing support.
If not available / installed fall back to the standard one without
geture typing.

Change-Id: I70a5f43386a9c72809a70bd286f3702378d6f9be
LatinIME: Allow importing external dictionaries

The code is already present but hidden in LatinIME debug settings
Enable the feature and improve the dialog message a bit

The user simply needs to have a .dict dictionary (one or more) in
the /Download folder of his storage.

Change-Id: I93f4be4c41c02ba6306c6a29cf4d1178dd9837b3