Add tracer configuration

The tracer can be configured with environment variables.
By default a no-op tracer is still create.

Change-Id: I508b69fdc62ff46f3978c6204824c4900a5c6e3c
Signed-off-by: Roni Riska <roni.riska@nokia.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6a8d101..e44fb55 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -42,7 +42,7 @@
 
 set (tracelibcpp_VERSION_MAJOR "0")
 set (tracelibcpp_VERSION_MINOR "0")
-set (tracelibcpp_VERSION_MICRO "3")
+set (tracelibcpp_VERSION_MICRO "4")
 set (tracelibcpp_VERSION_STRING
     "${tracelibcpp_VERSION_MAJOR}.${tracelibcpp_VERSION_MINOR}.${tracelibcpp_VERSION_MICRO}")
 
@@ -83,6 +83,7 @@
 option(WITH_TESTING "Include using testing support" OFF)
 
 include_directories ("${PROJECT_SOURCE_DIR}/include/tracelibcpp")
+include_directories ("${PROJECT_SOURCE_DIR}/src")
 
 add_library(tracelibcpp SHARED
     src/tracelib.cpp