Change yet again how page size is parsed, using bash built-in string processing. Last version was not working on MacOS since there is no `expr index` on BSD's expr. Tested on MacOS and Amazon Linux.

error message was outdated

using $BASENAME on help

- Does not require imagemagick anymore
- Uses cat + grep to get page size from pdf
- Does not use POSIX tr anymore (using bash string manipulation)
- Adding language variables to make sure our decimals use a point
- Binaries for ghostscript and bc are called from variables now, uses which to set

to make installation and uninstallation easier

- Supports MacOS  
- Supports filenames with spaces  
- Has parameters and options now  
- Can define optional output file  
- Help Info with parameter (-h)
- Define scale factor with parameter (-s factor)
- Print version with parameter -V
- Verbose output with parameter -v
- Don't use sed anymore (uses pure bash for what sed was used, or tr)
- New messages if failed dependencies
- Changed how page dimensions are obtained (still needs imagemagick)