made minor changes, corrected typo and grammar only

[jagottsicher]

minor stuff only.

• corrected "naivate" or something to "navigate" and here and there exchanged "... is :" to " ... is:" as a colon should stick without space to the last char before its use.
• codeblocks removed some useless tabs/spaces at the end of lines, but eventually I added a customized .gitignore which probably should not be merged. But feel free to use it.