[xmlsec] versioning and library naming policies

[Aleksey Sanin]

Hi, John!

I made changes to both 0.0.x branch and the 1.0.X trunk so now both
versions can live together on the same box. I've tried to minimize
changes for the existing library and only moved its include files to version
specific folder (see 0.0.15 release for details).

I would appreciate if you can take a look and see if this works for you. 
I could
not say it's fixed until you approve the result  since you was the one 
who have
asked about it :)

Thank you in advance,
Aleksey