merge: added info that hg help merge-tools shows the options for --tool

util: move checklink() to posix.py and return False on Windows Python added support for Windows 6.0 (Vista) symbolic links in 3.2 [1], but even these symbolic links aren't what we can expect from a canonical symbolic link, since creation requires SeCreateSymbolicLinkPrivilege, which typically only admins have. So we can safely assume that we don't have symbolic links on Windows. [1] http://docs.python.org/py3k/library/os.html#os.symlink

util: make 'hg log -d --2' abort (issue2734)