plugin: import with proper name

This is imporant for modules based on c as this names sets the initialization routine, which would not exist with this made-up name.
refactor: move plugin loading to plugin module
plugin: support search_paths

c-based plugins built using distutils goes into build/lib.*
refactor: split plugin.load
plugin: show where it is loaded from
log: further increase column width
refactor: move logging setup
plugin: must use plugin log

This worked by accident before refactoring
plugin: some docs for attribute
plugin: add deps variable
plugin: allow plugins in subdirectories
plugin: handle when deps is invalid
adding unit-testing
viz01: use new transition config
canvas: scroll more than 1 row at a time
viz01: fix viz01 config
canvas: support rowspan

Have a widget occupy more than one row.
plugin: text plugin supports writing text directly in config
Merge branch 'rowspan'