htmlgen: Allow specifying settings and output directory.
htmlgen: Allow specifying settings and output directory.

Signed-off-by: Tim 'mithro' Ansell <57310ee00039176189a7bd7b876cda4d0d2a19aa@mithis.com>

SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray,SymbiFlow/prjxray