It uses 'Note:' as a prefix as opposed to the common 'Warning:' to take
down the tone a bit.
It adds a warning for using -XHEAD on other methods becasue that may
lead to a hanging connection.
As the 'error' and 'mute' options are now part of the GlobalConfig,
rather than per Operation, updated the warnf() function to use this
structure rather than the OperationConfig.
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.
