Move subsurface-core to core and qt-mobile to mobile-widgets

Having subsurface-core as a directory name really messes with
autocomplete and is obviously redundant. Simmilarly, qt-mobile caused an
autocomplete conflict and also was inconsistent with the desktop-widget
name for the directory containing the "other" UI.

And while cleaning up the resulting change in the path name for include
files, I decided to clean up those even more to make them consistent
overall.

This could have been handled in more commits, but since this requires a
make clean before the build, it seemed more sensible to do it all in one.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

mobile-widgets/qml/StartPage.qml

@@ -0,0 +1,42 @@
+import QtQuick 2.5
+import QtQuick.Controls 1.2
+import QtQuick.Controls.Styles 1.2
+import QtQuick.Layouts 1.1
+import org.kde.kirigami 1.0 as Kirigami
+import org.subsurfacedivelog.mobile 1.0
+
+ColumnLayout {
+	id: startpage
+	width: subsurfaceTheme.columnWidth
+
+	function saveCredentials() { cloudCredentials.saveCredentials() }
+
+	Kirigami.Heading {
+		Layout.margins: Kirigami.Units.gridUnit
+		text: "Subsurface-mobile"
+	}
+	Kirigami.Label {
+		id: explanationText
+		Layout.fillWidth: true
+		Layout.margins: Kirigami.Units.gridUnit
+		Layout.topMargin: 0
+		text: "In order to use Subsurface-mobile you need to have a Subsurface cloud storage account " +
+		      "(which can be created with the Subsurface desktop application)."
+		wrapMode: Text.WordWrap
+	}
+	Kirigami.Label {
+		id: messageArea
+		Layout.fillWidth: true
+		Layout.margins: Kirigami.Units.gridUnit
+		Layout.topMargin: 0
+		text: manager.startPageText
+		wrapMode: Text.WordWrap
+	}
+	CloudCredentials {
+		id: cloudCredentials
+		Layout.fillWidth: true
+		Layout.margins: Kirigami.Units.gridUnit
+		Layout.topMargin: 0
+		property int headingLevel: 3
+	}
+}