Update install-mac-linux.sh

Added quotes around "%ANDROID_HOME%\platform-tools\adb" in case of file paths with spaces.

Added "#" comments for ease of debugging

Added functions to separate code into sections for ease of debugging

added initialization

Rewrote initialization so that ANDROID_HOME is cleared for compatibility.

Fixed wording so that the disclaimer section is more readable.

Added a proper bash exit for compatibility with other automation programs (or scripts)