Moved source files into "src/" subdirectory.

This move made in anticipation of adding a new "doc/"
subdirectory to contain documentation.
Added documentation template from "sphinx-quickstart".
Fixed syntax and path errors preventing imports.
Added first stab at real documentation.
Removed examples from main source tree.
Started move of instrument modules. Currently broken.
Continued reorganizing modules and packages.

Still to go: instruments/lakeshore, instruments/other and
instruments/srs.
Reorganized lakeshore/.
Finished reorganization.
Continued working on documentation.

Agilent docs are currently broken due to non-standard
indentation in docstrings.
Merge pull request #1 from cgranade/dev

Documentation and file restructure merged.