lib: remove some dead code (mu-str/utils)

Remove unused library code; recycle some electrons.

mu/mu-cmd-cfind.cc

@@ -32,10 +32,20 @@
 #include "utils/mu-util.h"
 #include "utils/mu-utils.hh"
 #include "utils/mu-error.hh"
-#include "utils/mu-str.h"
 
 using namespace Mu;
 
+/**
+ * macro to check whether the string is empty, ie. if it's NULL or
+ * it's length is 0
+ *
+ * @param S a string
+ *
+ * @return TRUE if the string is empty, FALSE otherwise
+ */
+#define mu_str_is_empty(S) ((!(S)||!(*S))?TRUE:FALSE)
+
+
 /**
  * guess the last name for the given name; clearly,
  * this is just a rough guess for setting an initial value.

mu/mu-cmd-extract.cc

@@ -21,7 +21,6 @@
 #include "mu-cmd.hh"
 #include "mu-config.hh"
 #include "utils/mu-util.h"
-#include "utils/mu-str.h"
 #include "utils/mu-utils.hh"
 #include <message/mu-message.hh>
 #include <regex>

mu/mu-cmd-find.cc

@@ -38,7 +38,6 @@
 
 #include "utils/mu-option.hh"
 #include "utils/mu-util.h"
-#include "utils/mu-str.h"
 
 #include "mu-cmd.hh"
 #include "utils/mu-utils.hh"

mu/mu-cmd-script.cc

@@ -32,7 +32,6 @@
 #include "mu-runtime.hh"
 
 #include "utils/mu-util.h"
-#include "utils/mu-str.h"
 
 #define MU_GUILE_EXT          ".scm"
 #define MU_GUILE_DESCR_PREFIX ";; INFO: "

mu/mu-cmd.cc

@@ -37,7 +37,6 @@
 #include "message/mu-mime-object.hh"
 
 #include "utils/mu-util.h"
-#include "utils/mu-str.h"
 
 #include "utils/mu-error.hh"
 #include "utils/mu-utils.hh"

mu/tests/test-mu-query.cc

@@ -33,7 +33,6 @@
 #include "test-mu-common.hh"
 #include "mu-query.hh"
 #include "utils/mu-result.hh"
-#include "utils/mu-str.h"
 #include "utils/mu-utils.hh"
 #include "mu-store.hh"