[Rd] Rcmd install mypkg

[Gabor Grothendieck]

I noticed that in "R version 2.4.0 alpha (2006-09-16 r39365)" on Windows XP
that I get this error:

C:\Rpkgs>Rcmd install mypkg
no Perl script 'install'

The same command worked with no error in 2.3.1pat.  If I capitalize
INSTALL it does work; however, this was not necessary previously.

Note that

C:\Rpkgs>Rcmd check mypkg

unlike install, still works in either lower or upper case in 2.4.0 alpha.