Specify versions of source code repositories

[pejalo]

After an unsuccessful attempt to update the TagLib template in this repository to create an amalgam of the latest release, I am trying to get this template working as-is with whatever version of TagLib was used at the time. Based on the timing and commit history of TagLibAmalgam I would expect this to work with version 1.7.1 or 1.7.2. However this template references files not present in either version, e.g. toolkit/tbytevectorstream.h, toolkit/tiostream.h, toolkit/tfilestream.h. 1.8 includes those files but the resulting amalgam will not compile because of other errors ("Redefinition of 'defaultStringHandler' with a different type").