Renamed slirp option 'dhcp' to 'dhcpstart' (similar to Qemu)
Ignore case when checking for slirp options
Improved slirp documentation


git-svn-id: svn://svn.code.sf.net/p/bochs/code/trunk@12227 6c8e4198-a580-4521-a02f-c9ae86df1db9