Add quotes to width and height argument, conforming to CLI tool

[yiufung]

Surprisingly CLI tool accepts width and height argument in string form. Instead of writing :width "1200", writing :width 1200 is more natural.

[lgfang]

Add quotes to width and height argument, conforming to CLI tool #11

Surprisingly CLI tool accepts width and height argument in string form. Instead of writing :width "1200", writing :width 1200 is more natural.

The above statements are incorrect as per my previous comments. I'd suggest changing them to the following (or similar) respectively:

Allow both decimal and string values for the option width/height

Currently, the options must be set using strings, say :width "1024". If we use a number instead like :width 1024, then we'll get the error "(wrong-type-argument sequencep 1024)". With this fix, both :width 1024 and :width "1024" will work.