Bug 8375: (follow-up) fix font code and alignment

Bug 8375: (follow-up) fix font code and alignment

This patch fixes two problems:
a) Bad PDF when using Helvetica font.
Current label code assigns 'italic' or 'oblique' variants
to title. Helvetica-Oblique was not defined, but is present

b) Bad alignment using center/right justification
Problem was bad font parameter passed to StrWidth
routine

To test:
1. Try making a batch using Helvetica, downloaded PDF do not open.
2. Try a batch of mixed scripts with layout alignment center or
   right, only latin scripts align almost correctly.
3. Apply the patch and update your koha-conf.xml to add Oblique variant
4. Try again 1, now PDF opens
5. Try 2, now alignment is correct

New problem (for another bug): DejaVuSans has a good
support for arabic, but not Oblique variant. As selection
of italic/oblique is hardcoded, now Arabic titles are
not displayed. I'll try to add a checkbox to select
or not this feature.

Added a FIXME for the hardcoded forced oblique -chris_n

Signed-off-by: Chris Nighswonger <cnighswonger@foundations.edu>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>