[OcrPlugin] Language Download

[dschoerk]

• Remove language files from this repo
• Add action to open language download dialog
• Add a list of languages + download buttons
• List available languages based on what is available on github https://api.github.com/repos/tesseract-ocr/tessdata/ abandoned for the reasons below

adding buttons to a table cell: https://stackoverflow.com/a/35084467

[dschoerk]

selected languages are now stored with the regular QSettings as a QStringList. the value of the stringlist is not correctly displayed and editable in the nomacs settings editor, but the values are saved and loaded correctly.

[dschoerk]

https://api.github.com/repos/tesseract-ocr/tessdata/contents
QNetworkAccessManager / QNetworkRequest fail to retrieve the above url.

QNetworkReply::errorString says "ssl handshake failed"
QNetworkReply::sslErrors is empty
the slot QNetworkReply::sslErrors(QNetworkReply*, QList) is not called
seems buggy to me :( was testing that with the official build qt5.10 build for msvc 2015x64

Downloading of the language files works via: https://raw.githubusercontent.com/tesseract-ocr/tessdata/master/