#101 Inconsistent default value for lfModifier distance

[letmaik]

At http://lensfun.sourceforge.net/manual/structlfModifier.html#a15fc45849ffb7f7f0f815025d4994ccd it says the default should be 1000 if not known.
In the linked example http://lensfun.sourceforge.net/manual/lenstool_8cpp-example.html#a38 a value of 1.0 is used.
This is confusing and should be aligned I think.

[seebk]

Now fixed in master.