Remember to use fseeko(), not fseek()

Fixes opening Hamamatsu NDPI slides > 2 GB and reading MIRAX PNG slides
with a level > 2 GB on 32-bit systems.

http://lists.andrew.cmu.edu/pipermail/openslide-users/2014-April/000772.html
tifflike: Drop redundant seek
hamamatsu: Always check fseeko() return value
Accept comma as decimal separator when parsing doubles

Aperio slides apparently leak the system locale into slide files.

Fixes #134.
Forbid calling fopen() and g_ascii_strtod()
sqlite: Add some missing includes
Forbid some additional library functions
Fix build from Git checkout with core.autocrlf=true