Increase maximum resolution in UI to 8640. (#1771)

A valid resolution for 8k Youtube Videos (in VR 180 format) is
8640 x 4320. Making Shotcut support up to 8640 pixels maximum resolution
allows such videos to be edited and rendered in Shotcut.

Author: geoff604

src/dialogs/customprofiledialog.ui

@@ -99,7 +99,7 @@
            <number>1</number>
           </property>
           <property name="maximum">
-           <number>8192</number>
+           <number>8640</number>
           </property>
           <property name="value">
            <number>16</number>
@@ -119,7 +119,7 @@
            <number>1</number>
           </property>
           <property name="maximum">
-           <number>8192</number>
+           <number>8640</number>
           </property>
           <property name="value">
            <number>9</number>
@@ -244,7 +244,7 @@
            <number>16</number>
           </property>
           <property name="maximum">
-           <number>8192</number>
+           <number>8640</number>
           </property>
           <property name="singleStep">
            <number>2</number>
@@ -267,7 +267,7 @@
            <number>1</number>
           </property>
           <property name="maximum">
-           <number>8192</number>
+           <number>8640</number>
           </property>
           <property name="singleStep">
            <number>2</number>

src/docks/encodedock.ui

@@ -707,7 +707,7 @@ with parallel processing enabled.</string>
                       <number>16</number>
                      </property>
                      <property name="maximum">
-                      <number>8192</number>
+                      <number>8640</number>
                      </property>
                      <property name="singleStep">
                       <number>2</number>
@@ -730,7 +730,7 @@ with parallel processing enabled.</string>
                       <number>1</number>
                      </property>
                      <property name="maximum">
-                      <number>8192</number>
+                      <number>8640</number>
                      </property>
                      <property name="singleStep">
                       <number>2</number>
@@ -903,7 +903,7 @@ with parallel processing enabled.</string>
                       <number>1</number>
                      </property>
                      <property name="maximum">
-                      <number>8192</number>
+                      <number>8640</number>
                      </property>
                      <property name="value">
                       <number>16</number>
@@ -923,7 +923,7 @@ with parallel processing enabled.</string>
                       <number>1</number>
                      </property>
                      <property name="maximum">
-                      <number>8192</number>
+                      <number>8640</number>
                      </property>
                      <property name="value">
                       <number>9</number>

src/widgets/avformatproducerwidget.ui

@@ -512,7 +512,7 @@
                 <number>1</number>
                </property>
                <property name="maximum">
-                <number>8192</number>
+                <number>8640</number>
                </property>
                <property name="value">
                 <number>16</number>
@@ -538,7 +538,7 @@
                 <number>1</number>
                </property>
                <property name="maximum">
-                <number>8192</number>
+                <number>8640</number>
                </property>
                <property name="value">
                 <number>9</number>