enable libpng configure for all solaris architectures
update README-Strawberry.txt
retry_update is now also active on Windows

Problems under Windows with t/entry.t test are rare, but may happen.
So retry_update is now active on all GUI platforms.
rename scaffolding script build -> build_ptk

On case insensitive file systems "build" could be mistaken as "Build", which
may confuse CPAN::Reporter when computing grades.
modernize README-ActiveState.txt

Now the MinGW ppm package is mentioned, along with the problems here.
The old and probably outdated Visual C++ instructions are moved to the
bottom.
INSTALL: simplified instructions on top
INSTALL: mention compiled third-party Tk modules
update Changes for Tk-804.031_502
inc VERSIONs