add some build system config files, improve .gitignore

src/.nuget/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Xamarin.GooglePlayServices" version="27.0.0.0" />
+</packages>

src/App1/Resources/menu/group.xml

@@ -1,10 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<menu xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:id="@+id/search"
-        android:icon="@android:drawable/ic_menu_search"
-        android:title="Search"
-        android:showAsAction="ifRoom"
-        android:actionViewClass="android.widget.SearchView" 
-    />
-    
-</menu>

src/App1/Resources/xml/searchable_app1.xml

@@ -1,14 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<searchable xmlns:android="http://schemas.android.com/apk/res/android"
-
-        android:label="@string/search_label"
-    android:hint="@string/search_hint" 
-    android:searchMode="showSearchLabelAsBadge"
-        android:searchSuggestAuthority="App1.SearchProvider"
-    android:searchSuggestSelection=" ?"
-    android:searchSuggestThreshold="2"
-    android:searchSuggestIntentAction="android.intent.action.VIEW"
-    android:searchSuggestIntentData="content://keepass2android.EntryActivity"
-
-        >
- </searchable>

src/KeePassLib2Android/packages.config

@@ -0,0 +1,3 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+</packages>

src/Kp2aBusinessLogic/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Xamarin.Android.Support.v4" version="23.1.1.0" targetFramework="MonoAndroid50" />
+</packages>

src/java/KP2ASoftkeyboard_AS/gradle.properties

@@ -0,0 +1 @@
+org.gradle.jvmargs=-Xmx1024m