Build: travis switch from Trusty to Xenial

.travis.yml

@@ -4,22 +4,13 @@ env:
   - HOME=/home/travis APPDATA=/home/travis LocalAppData=/home/travis
 
 sudo: required #false
-dist: trusty
+dist: xenial
 dotnet: 2.2.106
 mono:
 - latest
 os:
 - linux
 
-addons:
-  apt:
-    sources:
-    - sourceline: 'deb [arch=amd64] https://packages.microsoft.com/repos/microsoft-ubuntu-trusty-prod trusty main'
-      key_url: 'https://packages.microsoft.com/keys/microsoft.asc'
-    packages:
-    - dotnet-hostfxr-1.0.1
-    - dotnet-sharedframework-microsoft.netcore.app-1.1.2
-
 branches:
   except:
     - gh-pages

MathNet.Numerics.sln

@@ -35,6 +35,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Build", "Build", "{B54A0B40
 		global.json = global.json
 		paket.dependencies = paket.dependencies
 		paket.lock = paket.lock
+		azure-pipelines.yml = azure-pipelines.yml
 	EndProjectSection
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "TestData", "src\TestData\TestData.csproj", "{AF3253C9-4DB5-45A0-98CF-C105FDA9DA47}"