Improves MythTimer contstructor.

Many times a MythTimer is constructed and start() is called immediately afterward.
This adds a parameter to the constructor StartState, so instead of:
  MythTimer t;
  t.start();
  do_something();
  int e = t.elapsed();

you can write:
  MythTimer t(MythTimer::StartRunning);
  do_something();
  int e = t.elapsed();

This also reverts [9402858], which made starting the timer running the default.
The bug requiring that hack was fixed in [926464a].

This also allows you to define DEBUG_TIMER_API_USAGE and have MythTimer assert
that the timer is running when elapsed is called to catch timer API misuse.

mythtv/libs/libmythbase/mythtimer.cpp

@@ -22,6 +22,25 @@
 // MythTV includes
 #include "mythtimer.h"
 
+//#define DEBUG_TIMER_API_USAGE
+#ifdef DEBUG_TIMER_API_USAGE
+#undef NDEBUG
+#include <cassert>
+#endif
+
+/** Creates a timer.
+ *
+ *  If a start state of kStartRunning is passed in the timer is
+ *  started immediately as if start() had been called.
+ */
+MythTimer::MythTimer(StartState state) : m_offset(0)
+{
+    if (kStartRunning == state)
+        start();
+    else
+        stop();
+}
+
 /// starts measuring elapsed time.
 void MythTimer::start(void)
 {
@@ -69,7 +88,12 @@ void MythTimer::stop(void)
 int MythTimer::elapsed(void) const
 {
     if (!m_timer.isValid())
+    {
+#ifdef DEBUG_TIMER_API_USAGE
+        assert(0 == "elapsed called without timer being started");
+#endif
         return 0;
+    }
 
     int64_t e = m_timer.elapsed();
     if (!m_timer.isMonotonic() && (e > 86300000))

mythtv/libs/libmythbase/mythtimer.h

@@ -12,7 +12,12 @@
 class MBASE_PUBLIC MythTimer
 {
   public:
-    MythTimer() : m_offset(0) { m_timer.start(); }
+    typedef enum {
+        kStartRunning,
+        kStartInactive,
+    } StartState;
+
+    MythTimer(StartState state = kStartInactive);
 
     void start(void);
     int restart(void);

mythtv/libs/libmythbase/mythversion.h

@@ -12,7 +12,7 @@
 /// Update this whenever the plug-in API changes.
 /// Including changes in the libmythbase, libmyth, libmythtv, libmythav* and
 /// libmythui class methods used by plug-ins.
-#define MYTH_BINARY_VERSION "0.27.20130124-1"
+#define MYTH_BINARY_VERSION "0.27.20130127-1"
 
 /** \brief Increment this whenever the MythTV network protocol changes.
  *

mythtv/libs/libmythbase/test/test_mythtimer.h

@@ -56,13 +56,20 @@ class TestMythTimer: public QObject
         QVERIFY(t.elapsed() > 50);
     }
 
-    void TimeDoesNotElapseImmediatelyAfterConstruction(void)
+    void TimeDoesNotElapseImmediatelyAfterConstructionByDefault(void)
     {
         MythTimer t;
         usleep(52 * 1000);
         QVERIFY(t.elapsed() == 0);
     }
 
+    void TimeDoesNotElapsesImmediatelyAfterContructionIfIntended(void)
+    {
+        MythTimer t(MythTimer::kStartRunning);
+        usleep(52 * 1000);
+        QVERIFY(t.elapsed() > 50);
+    }
+
     void TimeElapsesContinually(void)
     {
         MythTimer t;