Merge pull request #727 from NiLuJe/master

Update koreader-base
add API to query battery status on Android
check battery status file
Adde DCREREADER_TWO_PAGE_THRESHOLD
Update credocument.lua
Added new functions to go to next/previous chapter that also work with 2-page layout
Use of new functions to jump to next/previous chapter that also works in 2-page mode
Merge pull request #729 from WS64/master

Added DCREREADER_TWO_PAGE_THRESHOLD and changed behaviour of next/previous chapter
Merge pull request #728 from chrox/master

add API to query battery status on Android
border Kobo Aura screen because of obscuration by black bezel
move offset functions to screen.lua because of Kobo Aura issues
Merge pull request #731 from WS64/master

Add white borders to Kobo Aura because of obscuration by black bezel
removed unnecessary variables
Added inverted landscape settings
Update TOC after changing screen mode
Update TOC after change of hyphenation
Merge pull request #732 from WS64/master

Update TOC settings after some screen mode/hyphenation changes
prompt users to turn on Wifi if network is unreachable
no need to translate trademarks
add minibar height into overlap height