Merge pull request koreader#965 from chrox/collapsible_toc

fix koreader#959

Merge pull request koreader#955 from chrox/network_proxy

http proxy support by setting NETWORK_PROXY variable

Merge pull request koreader#936 from WS64/master

fix the nil tags data bug

Merge pull request koreader#932 from chrox/master

fix run out of memory when receiving large files from Calibre

Merge pull request koreader#894 from chrox/fix_872

fix koreader#872

Merge pull request koreader#890 from chrox/fix_772

fix koreader#772

Merge pull request koreader#867 from chrox/fix_863

register opened document in documentregistry

Merge pull request koreader#862 from chrox/fix_858

don't share info field in document

Merge pull request koreader#855 from WS64/master

Only use registered file types in search

Merge pull request koreader#836 from chrox/fix_835

fix koreader#835