Allow indentation of options in .ctags files

[jfelchner]

This is a continuation of #407

It'd be nice to be able to add indentation to .ctags files for better organization. Currently if an option is indented, it causes a ctags: Warning: Ignoring non-option in ./.ctags warning.

[masatake]

Thank you for good idea.

Those who have interests in implementing this feature, I try to give hints:

1. add 'trimHeaderWhitespace' or something boolean parameter to nextFileLine function in args.c:
   if trimHeaderWhitespace is true, call vStringStripLeading before strcpy:

   strcpy (result, vStringValue (vs));
   

2. From nextFileLineSkippingComments, pass TRUE as the second argument when calling nextFileLine.

3. Write Tmain test case.

4. Send a PR. Don't forget "Close Allow indentation of options in .ctags files #409" to you comment.

Not so difficult. Any volunteer? We are looking for not only a person who can review parser code but also who has interests core part of ctags.

[jfelchner]

@masatake amazing! Thank you!