tidy tesseract(1) adding missing options

doc: Remove unsupported font name

Fix typo in comment

Fix this warning from doxygen:

    warning: doxygen no longer ships with the FreeSans font.
    You may want to clear or change DOT_FONTNAME.
    Otherwise you run the risk that the wrong font is being used for dot generated graphs.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

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

Added extra Init that takes a memory buffer or a filereader function pointer to enable read of traineddata from memory or foreign file systems. Updated existing readers to use TFile API instead of FILE. This does not yet add big-endian capability to LSTM, but it is very easy from here.

opencl: Remove more unused functions and related code

ccstruct: Fix Leptonica data type

opencl: Fix crash on hosts with no OpenCL platform

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

L_Bmf works for C++ code, but the common form is L_BMF, so use that.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

A Tesseract binary with OpenCL support can also run on a host without
any OpenCL platform, as it simply uses the normal CPU based code.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

opencl: Remove unused code

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

Remove also the related OpenCL kernel code kernel_RGBToGray.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Leptonica related updates

Since commit 245eebdf, Tesseract 3.05
requires Leptonica 1.74, so this is not a new requirement for 4.00.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Tesseract requires Leptonica 1.74 or newer,
so that code is no longer needed.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Use the latest version which is available.
Remove also some unneeded whitespace.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

Cmake install

Small Typo Fix

Fix typo

Implement and contribute one small typographical fix, thereby improving the readability of the script's check
for the existence of the `m4` top-level directory.

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

testing: Fix warnings from shellcheck

Fix these kinds of warnings:

SC2002: Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead.
SC2086: Double quote to prevent globbing and word splitting.
SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

[4.00] Fix #786 OpenCL linkage fails on macOS

Also needed for 4.00.

README: Update stable version

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

opencl: Add missing TIFF library for macOS

The OpenCL code of Tesseract uses TIFF functions, but the TIFF library
was not added to the linker flags for macOS.

This fixes builds with OpenCL on Mac.
Signed-off-by: NStefan Weil <sw@weilnetz.de>

README.md: Add subsection 'Supported compilers'