test_text Modify filter warning regex

The regex will not match in python 2 since this is a unicode literal.
Fix that by adding an optional 'u' to the regex.
Merge pull request #3408 from jenshnielsen/Font_warn

TST : Filter warnings in test suite

test_text Modify filter warning regex
Merge pull request #3262 from mdboom/min-freetype-version

BLD : reduces the minimum version of freetype

1.4.0 RC1: --ftversion vs --version freetype version
prepare a fresh git checkout for doc build on MS windows
fix winbuild link
remove libpng version probing on windows