Add GoogleTest infrastructure

Added CMake option to use system ICU library

List available languages recursively

WIP: Chore/cleanup compiler warnings

move code around so that list-langs will work without an English traineddata file

suppress a strict aliasing warning; the original author was very clear about the nature of the problematic code

Tesseract supports hierarchies of languages and uses them since
the new files best/*.traineddata were added.

Now `tesseract --list-langs` also shows any traineddata files in
subdirectories of the tessdata directory.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Change default resolution from 70 to 300 dpi

The default resolution is used for images without an explicit resolution
or with an unreasonable resolution (smaller than 70 or larger than 2400).
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Fix broken build for Windows

Windows does not provide a mkdir function with two parameters.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

std::max build fix.

Define std::max under VS2017 x64

Rewrote the recoder to use an encoding based on wubi instead of radical-stroke index, changed from normalized to unnormalized unichar representation

Changed the way unicharsets are handled to allow support for the ™ character. Can find the issue where it was requested.

Signed-off-by: NStefan Weil <sw@weilnetz.de>

The submodule is build automatically as soon as it exists.
Signed-off-by: NStefan Weil <sw@weilnetz.de>