FT8 support: optimize FFT buffers and plan allocation

ft8/ft8plans.cpp

@@ -38,7 +38,7 @@ FT8Plans::~FT8Plans()
     qDebug("FT8::FT8Plans::~FT8Plans: %lu plans to delete", m_plans.size());
 
     for (auto& plan : m_plans) {
-        delete plan;
+        delete plan.second;
     }
 }
 
@@ -55,19 +55,14 @@ Plan *FT8Plans::getPlan(int n)
 {
     QMutexLocker mlock(&m_globalPlanMutex);
 
-    for (auto& plan : m_plans)
-    {
-        if ((plan->n_ == n) && (plan->type_ == Plan::M_FFTW_TYPE)) {
-            return plan;
-        }
+    if (m_plans.find(n) != m_plans.end()) {
+        return m_plans[n];
     }
 
     fftwf_set_timelimit(5);
 
-    Plan *p = new Plan(n);
-    m_plans.push_back(p);
-
-    return p;
+    m_plans[n] = new Plan(n);
+    return m_plans[n];
 }
 
 }