ENH: Register GE Image formats

The GE5ImageIO is useful for reading the VisibileHuman radiological
data.

Change-Id: Ica870415ffe4f081746e3f891b5b59a4210e34b1
COMP: Suppress warning for using extern template instantiation

The patch addresses the following warning:
itkMetaDataObject.h(201) : warning C4231: nonstandard extension used :
'extern' before template explicit instantiation

Change-Id: Ia8538e7cf90fae3b0989677dbf77dba634d0f2c7
Merge topic 'RegisterGEImageIOFactories'

80cacdc7 ENH: Register GE Image formats
Merge topic 'FixExternNonStandardWarning'

aabbdfc6 COMP: Suppress warning for using extern template instantiation