DataFactory changes for Performance improvement

Hi,
Better formatted diffs as attachment.

net.outer_planes implementation of Stream is a
DataFactoy  by itself, Since AbstractStream extends
from DataFactory.  
Since DataFactory data remains the same most of the
time,  we can optimize memory by sharing the base set
of Registered elements and namespace mappings.

if we do create lot of streams in the same JVM, then
it certainly saves lot of memory.

I have modified the Datafactory to hold a reference to
a base datafactory, which is readonly. If a specific
stream adds new elements or namespaces, new
datastructures are created appropriately.

Attached the diffs. These diffs are against 0.13.2
version

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DataFactory diff
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15a16
> import java.util.Collections;