tests: Add a new database field to DTO3 in test.dc.
tests: Add (failing) DBServer test demonstrating the "SET_FIELDS cannot set previously-unset fields" bug.
Tests: Add new classes to test.dc with the clrecv keyword for test_clrecv.
YAMLDatabase: Fix set_fields bug causing updates on empty fields to be ignored.
Tests: Write stateserver unittest for clrecv keyword.
Tests: Add cleanup to ss test_clrecv
Stateserver: Implement clrecv.
Tests: Fix ChannelConnection.clear_channels().
Readme: Add clrecv to the DC File documentation, cleanup the keyword descriptions
Merge pull request #113 from Astron/dbserver-fix

Fix YAML database server bug.
Build Instructions: Add separate doc folder for building instructions.  Add Linux/Make guide.
Build Instructongs: For Linux/Make, fix .git/info/exclude section and add link to readme.
Update readme.md
Readme: Add link to building instructions documentation.
Build Instructions: Add visual studio.
BuildingReadme: Add VS hyperlink.
Build Instructions: Updated visual studio instructions for cmake.
Fix `Compiling` header.
Fix compile types in VS instructions, handled by VS not CMake
Merge pull request #116 from Astron/build-instructions

More detailed instructions for building Astron