1 - str2offset() no longer accepts negative numbers since offsets are by
nature positive.
2 - introduced str2unum() for the command line parser that accepts
numericals which are not supposed to be negative, so that it will
properly complain on apparent bad uses and mistakes.
Bug: http://curl.haxx.se/mail/archive-2012-07/0013.html
Configuration files such as curl_config.h and all config-*.h no longer exist
nor are generated/copied into 'src' directory, now these only exist in 'lib'
directory from where curl tool sources uses them.
Additionally old src/setup.h has been refactored into src/tool_setup.h which
now pulls lib/setup.h
The possibility of a makefile needing an include path adjustment exists.
Fix the str2num() function to not check if the input string starts with a
digit, since strtol() supports numbers prepended with '-' (and '+') too.
This makes the --max-redirs option work as documented.
