Add Xojo language support

[kmaehashi]

Add support for Xojo language, formerly called REALbasic (which is already in languages.yml).

Some wild examples:

• https://github.com/Hawkcode/MemberTree
• https://github.com/oleman108/imSplitter
• https://github.com/Olivier61/Icare---GitHub
• https://github.com/paullefebvre/xojotest
• https://github.com/jcowgar/xojo-format-code
• https://github.com/LyricsMaster/COMProxy

The example script is taken from http://en.wikipedia.org/wiki/Xojo

[kmaehashi]

List of extensions are available in the following PDF reference:
User Guide: Book 1: Fundamentals: pp.56-57
http://41160df63757fc043cfd-66287f38a83954e31a54d1dbe33e0650.r4.cf2.rackcdn.com/Documentation/EN-PDF/UserGuide-Fundamentals.pdf

[pchaigno]

@kmaehashi You should only add Xojo code source's extensions in languages.yml.

[kmaehashi]

@pchaigno Thanks, I removed extensions that are not in source format.

[arfon]

Thanks @kmaehashi. Could you please add at least 1 example file for each file extension you list?

[kmaehashi]

@arfon Thanks for review, I added 5 more samples.

[arfon]

👍 thanks.