Inline.pm - Alter regex in sub read_DATA()

Done to address a bug in handling of any symbols that
begin and end with double underscores.
Also bump version to 0.52_01
MANIFEST - add new file

Added:
C/t/21read_DATA.t
Changes - Update
C/t/21read_DATA.t - new test script.

Test case for the read_DATA() bug.
C/C.pm - update version number to 0.52_01.
C/Changes - Update
lib/Inline/MakeMaker.pm - bump version to 0.52_01
lib/Inline/MakeMaker/Changes - Update
Inline.pod - Update copyright to include 2013.