src: Reorganizing source code in preparation to merge NRD code

Note that as of this commit, there are several changes in location of
compiled binaries in `build/` folder:

* `nfd` has been moved to `build/bin/nfd`
* `unit-tests` has been split into `unit-tests-core` and `unit-tests-daemon`

Change-Id: I2c830c117879edbaa5457d6423c13f0273285919
Refs: #1486
diff --git a/docs/doxygen.conf b/docs/doxygen.conf
index 1a46ada..a6a9a38 100644
--- a/docs/doxygen.conf
+++ b/docs/doxygen.conf
@@ -142,7 +142,7 @@
 # will be relative from the directory where doxygen is started.
 # This tag requires that the tag FULL_PATH_NAMES is set to YES.
 
-STRIP_FROM_PATH        = daemon/
+STRIP_FROM_PATH        =
 
 # The STRIP_FROM_INC_PATH tag can be used to strip a user-defined part of the
 # path mentioned in the documentation of a class, which tells the reader which
@@ -733,7 +733,7 @@
 # spaces.
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = daemon/
+INPUT                  = core/ daemon/
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses