Two-Arg Long Command Line Options Allowed

In Texis version 8 and later, many Texis executables also allow the two-argument form of long command-line options that take a value. E.g. in addition to the "--install-dir=/texis/install/dir" assignment form historically supported, in version 8 "-install-dir /texis/install/dir" may also be given. This can make generating Vortex command lines for <exec> easier. See the individual executables command-line help for details.