Capitalization rules should ignore filenames & URLs

[infotexture]

The incorrect-capitalization rule currently complains about words from the specified capitalization list even when they appear in filenames:

     [echo]   Line 40: filepath - [incorrect-capitalization] 
     [echo] The word 'XML' is incorrectly capitalized in the following text: 
     [echo] 
     [echo] plugin.xml.

The same issue applies to instances of these words within URLs:

     [echo]   Line 23: dd - [incorrect-capitalization] 
     [echo] The word 'XML' is incorrectly capitalized in the following text: 
     [echo] 
     [echo] The DITA-OT project archive at dita.xml.org provides news about earlier toolkit releases  […] 

The easiest fix might be to only flag incorrect capitalization for words surrounded by whitespace, so in this case only xml would be treated as incorrect, but plugin.xml or dita.xml.org would be accepted.