Don't propagate HubConnector exceptions

This is to satisfy the principle that logger code should not throw
exceptions.
Improve HubConnector logging
Removed .NET 4.0 and SignalR submodule

* SignalR is now provided through a NuGet package, like usual. The
  version changed, so a few modifications were made to the code.

* Removed all the .NET 4.0 projects, because they were too much work to
  maintain (for now, at least).

* Removed ConcurrentSpeedTest.

* Update version to 0.7.2.27
Fix bug in BufferingLogger

Update version to 0.7.2.28
Better consumer logging
Extract a covariant interface from SRR
[in progress] Working on SqlSelectDef
Rewrite of Log5; Paging; PairedStream

Too many changes

* Rewrite of Log5, and removal of the old PROCESS library, which is now
  subsumed into Log5.

* Add PairedStream - this class provides paired input and output
  streams. Anything written to the input stream can be read from
  the output stream.

* Add Pager - This allows for efficient paging through a SQL table.

* Add ImmutableJsval - This behaves much like Jsval when read, but
  any given ImmutableJsval object cannot be modified.

* Improve SRR classes.

* Add IDescribable - this interface provides recursive description of
  an object and all IDescribables related to it.