Trivial fixes for C89 compliancy
Fixes possible issues with Wget running in a turkish locale
Aesthetic changes to progress bar
Add the -Wextra flag by default

After the Spring Cleaning on warnings in early 2014, GCC and Clang emit
only about two warnings when compiling Wget with -Wall -Wextra.

Enable both these flags by default so that new warnings in these areas
are more prominent.
Autotoolize configure.ac
Use pkg-config for libpsl checking
Add po/stamp-po to gitignore
Fix C89 issue in http.c found by MSVC 16
Removed form feeds from sources and NEWS
Fix libpsl<0.6.0 detection in configure.ac
Assume large-file support for WINDOWS
Fix code for undefined USE_NLS_PROGRESS_BAR in progress.c

Reported-by: Gisle Vanem