Add support for VS 2019

One thing of interest is that when VS 2019 produces a solution (.sln)
file, it gives it this version heading:

Microsoft Visual Studio Solution File, Format Version 12.00

The other IDE generation files such as msvc141.lua emit higher numbers
than 12 (eg msvc141.lua emits 14.0). VS 2019 refuses to open .sln files
with numbers higher than 14.00, but it seems unlikely that the versions
between 12 to 14 make any difference. I've made the 2019 version 12.00,
for consistency with the native values produced by the IDE, but I'm not
sure if this is correct.

scripts/tundra/ide/msvc-common.lua

@@ -516,9 +516,11 @@ function msvc_generator:generate_project(project, all_projects)
   p:write(' DefaultTargets="Build"')
 
   -- This doesn't seem to change any behaviour, but this is the default
-  -- value when creating a makefile project from VS2013, VS2015 and VS2017
-  -- wizards.
-  if VERSION_YEAR == '2017' then
+  -- value when creating a makefile project from VS2013, VS2015, VS2017,
+  -- and VS2019 wizards.
+  if VERSION_YEAR == '2019' then
+    p:write(' ToolsVersion="16.0"')
+  elseif VERSION_YEAR == '2017' then
     p:write(' ToolsVersion="15.0"')
   elseif VERSION_YEAR == '2015' then
     p:write(' ToolsVersion="14.0"')
@@ -542,11 +544,13 @@ function msvc_generator:generate_project(project, all_projects)
   p:write('\t</ItemGroup>', LF)
 
   p:write('\t<PropertyGroup Label="Globals">', LF)
-  if VERSION_YEAR == '2017' then
+  if VERSION_YEAR == '2019' then
+    p:write('\t\t<VCProjectVersion>16.0</VCProjectVersion>', LF)
+  elseif VERSION_YEAR == '2017' then
     p:write('\t\t<VCProjectVersion>15.0</VCProjectVersion>', LF)
   end
   p:write('\t\t<ProjectGuid>{', project.Guid, '}</ProjectGuid>', LF)
-  if VERSION_YEAR == '2017' then
+  if VERSION_YEAR == '2019' or VERSION_YEAR == '2017' then
     p:write('\t\t<Keyword>Win32Proj</Keyword>', LF)
   else
     p:write('\t\t<Keyword>MakefileProj</Keyword>', LF)
@@ -581,13 +585,15 @@ function msvc_generator:generate_project(project, all_projects)
       p:write('\t\t<PlatformToolset>v140</PlatformToolset>', LF) -- I have no idea what this setting affects
     elseif VERSION_YEAR == '2017' then
       p:write('\t\t<PlatformToolset>v141</PlatformToolset>', LF) -- I have no idea what this setting affects
+    elseif VERSION_YEAR == '2019' then
+      p:write('\t\t<PlatformToolset>v142</PlatformToolset>', LF) -- I have no idea what this setting affects
     end
     p:write('\t</PropertyGroup>', LF)
   end
 
   p:write('\t<Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />', LF)
 
-  if VERSION_YEAR == '2017' then
+  if VERSION_YEAR == '2019' or VERSION_YEAR == '2017' then
     for _, tuple in ipairs(self.config_tuples) do
       p:write('\t<ImportGroup Label="PropertySheets" Condition="\'$(Configuration)|$(Platform)\'==\'', tuple.MsvcName, '\'">', LF)
       p:write('\t\t<Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists(\'$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props\')" Label="LocalAppDataPlatform" />', LF)

scripts/tundra/ide/msvc142.lua

@@ -0,0 +1,7 @@
+-- Microsoft Visual Studio 2019 Solution/Project file generation
+
+module(..., package.seeall)
+
+local msvc_common = require "tundra.ide.msvc-common"
+
+msvc_common.setup("12.00", "2019")

scripts/tundra/tools/msvc-vs2019.lua

@@ -0,0 +1,8 @@
+
+module(..., package.seeall)
+
+local vscommon = require "tundra.tools.msvc-vscommon-next"
+
+function apply(env, options)
+  vscommon.apply_msvc_visual_studio("2019", env, options)
+end