Clean up whitespace, spelling/grammar, unused things, scope, shadowing, checks, file opens

[pabs3]

• Remove trailing whitespace
• Remove whitespace from arrays
• Split up a long line
• Fix indentation
• Uppercase the manual page document title
• Fix typos
• Remove an unused import
• Remove unused struct member
• Reduce scope of some variables
• Remove unnecessary pointer check
• Avoid using the name of a function for a variable within that function
• Modernise Perl file open calls
• Only check trurl.c for spelling errors once