Spatialite open

This is an attempt to correct 2 problems

1) Raster-Datasource has more than one Image
* an unique Name did not show up in `SourcesTreeListActivity` and only the first was selectable
   * SpatialTable.getTitle() was added
      * returning the already existing `title`
         * which is either a 'Short description' 
            * OR if missing, the TableName

 `SourcesTreeListActivity` will now show this title
* when selected, getTitle() will be used to retrieve the RasterTable
* getTitle() is stored in the selected preferences

2) MessageBox `ERROR null`
* has occurred, possibly due to the max. connections restriction in spatialite 
   * database.open was **not** inside a try/catch [SpatialiteDatabaseHandler]
   * the jsqlite driver did not check if `p_cache` was valid (to many connections)
      * which spatialite **must** have to start correctly
   * the jsqlite internal `throwex` seems to call the java exception logic
      * if `p_cache` is NULL, `throwex` will be called
         * SpatialiteDatabaseHandler will set `isDatabaseValid = true`
            * when the exception is not call
         * `DaoSpatialite.checkDatabaseTypeAndValidity` will only be called if (isValid())

(I just saw the the 'open' command is being called twice, I will update this)

This should MessageBox `ERROR null` problem.
Also it will catch any other problems that may have occurred during the open process
* there are 3 other `throwex`  during open, including invalid file-name

2b) a `bounds_west` was set to a positive number
* bounds_west = -180.0;

**Note**
* in the jsqlite driver a connection counter has been added with a fetch routine
   * Database.java now has a db_connections() to retrieve this value
      * at the moment not used, but may be needed in the future