ERT-700: Added method EclGrid.getNodePos(i,j,k)
ERT-700: New function layer_replace_cell_values()
ERT-700: Changed fault_block_layer_scan_kw()

With this change the fault_block_layer_scan_kw() function uses a
temporary layer instance - this implies that:

 1. The block_id values in the fault_block_layer are *completely*
    unrelated to the original values in the ecl_kw instance.

 2. The blocks in the fault_block_layer are guaranteed to be singly
    connected.

 3. Singly connected fault blocks are generated also for the cells which
    originally have value 0.
ERT-700: Added EclKw.getEclType() method
ERT-700: Added fault_block_layer_export -> ecl_kw
ERT-700: Initialize numeric ecl_kw to zero

Have changed the data allocation for ecl_kw to include a memset( 0 ),
which ensures that the numerical type ECL_INT_TYPE, ECL_REAL_TYPE and
ECL_DOUBLE_TYPE are initialized to numerical zero.
ERT-700: Added polyline intersects method