Merge pull request #949 from hwhw/master

adapt to new freetype text rendering without background
fix fgcolor of inputbox is always 0.0
strip generic punctuation (U+2000 - U+206F) in lookup word
This should fix #921.
check if last opened file exists before opening it
This should fix #916.
get rid of query filed of baseurl when building href
otherwise there will be "?offset=90" query in downloading href
for calibre opds server which doesn't accept the url

This should fix #950.
Merge pull request #951 from chrox/fix_fgcolor

fix fgcolor of inputbox is always 0.0
http proxy support by setting NETWORK_PROXY variable
This should implement feature request in #919.
Merge pull request #952 from chrox/fix_921

strip generic punctuation (U+2000 - U+206F) in lookup word
Merge pull request #953 from chrox/fix_916

check if last opened file exists before opening it
Merge pull request #954 from chrox/fix_950

get rid of query filed of baseurl when building href
Merge pull request #955 from chrox/network_proxy

http proxy support by setting NETWORK_PROXY variable
benchmark has no specifications so won't be run by default
don't open SDL if input device is dummy
make coverage target for code coverage for the unit test
so that we can easily find which module needs unit test

In order to run 'make coverage' `luacov` need to be installed
with 'sudo luarocks install luacov'.
install luajit for luacov in Travis
add coveralls badge to show coverage number
Update README.md
Merge pull request #956 from chrox/coverage

code coverage target for the unit test
coverage test only sources from frontend and plugins
refactoring unit testsuite