Additional work for #913 : allow empty framework conditionals in paket.template

[seanamosw]

This is some additional work for #913 to allow you to specify empty framework conditionals in your paket.template file.

type file
id My.Thing
authors Bob McBob
description
    A longer description
    on two lines.
version
    1.0
dependencies
    framework: net461
    framework: net45
        FSharp.Core 4.3.1
    framework: netstandard11
        FSharp.Core 4.3.1

This results in a framework group with no dependencies.

    <dependencies>
      <group targetFramework="net461" />
      <group targetFramework="net45">
        <dependency id="FSharp.Core" version="4.3.1" />
      </group>
      <group targetFramework="netstandard1.1">
        <dependency id="FSharp.Core" version="4.3.1" />
      </group>
    </dependencies>

[seanamosw]

Build failure on Travis looks like a transient timeout

[seanamosw]

In c46ae74 I fixed an existing crash defect when specifying a global group/dependency.

Example:

dependencies
    MyDep 1.0.0
    framework: net45
        FSharp.Core 4.3.1
    framework: netstandard11
        FSharp.Core 4.3.1
Crash!

This now allows you to do:

    <dependencies>
      <group>
        <dependency id="MyDep" version="1.0.0" />        
      </group
      <group targetFramework="net45">
        <dependency id="FSharp.Core" version="4.3.1" />
      </group>
      <group targetFramework="netstandard1.1">
        <dependency id="FSharp.Core" version="4.3.1" />
      </group>
    </dependencies>

I think this now covers all dependency group cases.

[forki]

Thanks so much!