Merge pull request #49 from chrox/master

update k2pdfopt to version 1.66
Fix segfault in util.df and improve performance by struct preallocation (see #46)
Move lulip.lua to koreader-base
Merge pull request #50 from thotypous/ffi-util-fix

Fix segfault in util.df and improve performance by struct preallocation (see #46)
Merge pull request #51 from thotypous/lulip-move-base

Move lulip to koreader-base
fix typo
Merge pull request #52 from hwhw/master

fix typo in lulip.lua
Merge pull request #54 from chrox/master

register external font defined in EPUB style sheet
Make util.isEmulated return a boolean.

Some places in koreader code were using it as an integer, another places were using it as a boolean.
Make it a boolean. This fixes part of koreader#20.
Merge pull request #55 from thotypous/frontlight-fixes

Make util.isEmulated return a boolean.
Implement util.realpath
Merge pull request #56 from thotypous/realpath

Implement util.realpath
update libk2pdfopt for slightly better memory footprint