Add v1.50 cimgui.so, update assembly version.

Author: mellinoe

deps/cimgui/ubuntu.14.04-x64/cimgui.so

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <Description>A .NET wrapper for the dear ImGui library.</Description>
-    <VersionPrefix>0.2.1</VersionPrefix>
+    <VersionPrefix>0.3.0</VersionPrefix>
     <Authors>Eric Mellino</Authors>
     <TargetFramework>netstandard1.1</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>