tesseractmain: Prettify help message
tesseractmain: Prettify help message

Commit 99110df75781c6907c84a3d23695a6900b933a97 improved the help text
in several aspects, but also introduced new inconsistencies which this
patch tries to fix.

* Align columns (this needed replacing tabs by spaces).
* Start explaining text with uppercase.
* Replace "the stdout" by "stdout.
* Small changes in help text for page segmentation modes.
* Split options in OCR options and single options
  (partially revert commit 99110df75781c6907c84a3d23695a6900b933a97).

In addition, whitespace characters at end of lines were removed.

Signed-off-by: Stefan Weil <8d4c780fcfdc41841e5070f4c43da8958ba6aec0@weilnetz.de>

tesseract-ocr/tesseract,tesseract-ocr/tesseract,jbarlow83/tesseract,UB-Mannheim/tesseract,amitdo/tesseract,stweil/tesseract,stweil/tesseract,amitdo/tesseract,stweil/tesseract,stweil/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,UB-Mannheim/tesseract,jbarlow83/tesseract,tesseract-ocr/tesseract,tesseract-ocr/tesseract,stweil/tesseract,jbarlow83/tesseract,amitdo/tesseract,UB-Mannheim/tesseract,amitdo/tesseract,tesseract-ocr/tesseract,amitdo/tesseract,jbarlow83/tesseract,jbarlow83/tesseract