improve Makefile install

[hugy718]

quick fix of #154

[indutny]

Hello! Thank you for this PR. I just tried to run install with -D on macOS, and I don't think it works:

% install -D
install: illegal option -- D
usage: install [-bCcpSsv] [-B suffix] [-f flags] [-g group] [-m mode]
               [-o owner] file1 file2
       install [-bCcpSsv] [-B suffix] [-f flags] [-g group] [-m mode]
               [-o owner] file1 ... fileN directory
       install -d [-v] [-g group] [-m mode] [-o owner] directory ...

It is not on the man page either...

[hugy718]

Thanks for pointing out that. I changed to use -d to create directories before copy instead of -D.

[ShogunPanda]

LGTM!