Moved all shell related scripts to the shell directory
Updated the install instructions
Generalized some scripts for bash/zsh usage
Updated the install instructions
Added a general shell settings file for bash/zsh
Moved the shell specific stuff into subdirectories
Added the zsh scripts
Fixed a wrong path
Removed old aliases for MacOS X
Converted the bash if statements to zsh if statements
Fixed the wrong source paths
Moved the aliases into the shell_settings file