protected call of mupdf.renderImage
fix #1028
update base to use new libcrengine
Merge pull request #1030 from chrox/fix_1028

fix #1028
install nasm in Travis
Merge pull request #1031 from chrox/travis_nasm

install nasm in Travis
fix #1028 by trying load libpthread.so.0 on Kobo devices
Merge pull request #1032 from chrox/fix_1028

fix #1028 by trying load libpthread.so.0 on Kobo devices