improve combobox speed and autocompletion

.gitignore

@@ -1,3 +1,4 @@
+Makefile
 porymap.pro.user
 *.autosave
 *.stash

forms/tileseteditor.ui

@@ -206,7 +206,7 @@
               </widget>
              </item>
              <item row="3" column="0" colspan="3">
-              <widget class="QComboBox" name="comboBox_metatileBehaviors"/>
+              <widget class="NoScrollComboBox" name="comboBox_metatileBehaviors"/>
              </item>
              <item row="0" column="0">
               <widget class="QLabel" name="label_4">

src/ui/noscrollcombobox.cpp

@@ -1,10 +1,21 @@
 #include "noscrollcombobox.h"
 
+#include <QCompleter>
+
 NoScrollComboBox::NoScrollComboBox(QWidget *parent)
     : QComboBox(parent)
 {
     // Don't let scrolling hijack focus.
     setFocusPolicy(Qt::StrongFocus);
+
+    // Make speed a priority when loading comboboxes.
+    setMinimumContentsLength(20);// an arbitrary limit
+    setSizeAdjustPolicy(QComboBox::AdjustToMinimumContentsLength);
+
+    // Allow items to be searched by any part of the word, displaying all matches.
+    setEditable(true);// can set to false manually when using
+    this->completer()->setCompletionMode(QCompleter::PopupCompletion);
+    this->completer()->setFilterMode(Qt::MatchContains);
 }
 
 void NoScrollComboBox::wheelEvent(QWheelEvent *event)