Fixed linkage problem in Windows

Change-Id: I66f0cc98129cb70aae15d94cdbf19dc2d5839f55
Improved comment handling

There were some problems with how comments were read and written.
Fixed these problems for comments that precede a value. These
changes were submitted upstream to jsoncpp, but have not been
merged (see http://sourceforge.net/p/jsoncpp/patches/25/).

Change-Id: I6235519a21d6897eb81a3987835794acf4844167
Merge topic 'jsoncpp-improvements' into master

d4d486aa Improved comment handling
36d9e0ec Fixed linkage problem in Windows