BuiltIn: Little doc cleanup.

- Use Unicode escapes instead of module level encoding with non-ASCII chars.
- Whitespace in examples.
INSTALL: Mention Py3 port also under Python installation section
UG: Clean-up tag pattern section in order to make it easier to add more content.
UG: Document that tags with AND/OR/NOT should be used as lower case with tag patterns.

Resolves issue #1845.
Removed old and totally outdated packaging instructions. BUILD.rst contains updated information.
rm outdated nsn icon
include packaging instructions and utilities in source distribution
tasks.py: Little code/doc cleanup
UG: Enhance suite init file docs.

Includes better explanation how to share kws/vars using resources files. Fixes #1851.
fix a minor problem in Process, where minimum wait time could be longer than timeout time
the timeout on process timeout tests was not long enough to let the process actually write the output
cleanup to process waiting
DateTime: Fixed epoch related tests that were incorrectly DST dependent
Libdoc: Enhanced dynamic library tests
Allow setting test library documentation dynamically in __init__.

Earlier __doc__ was read from library classes, now it is read from
instances. Fixes #1859.
Fix installation with Python/Jython 2.5. Fixes #1842.
utests: extract method
Logging: Unregister RobotHandler after execution. Fixes #1821.

RobotHandler takes care of forwarding messages logged by the standard
logging module to Robot's log. It was not unregistered after
execution, and thus there were problems when executing tests multiple
times in same process if logging module actually was used.
API docs: Remove RF code syntax highlighting that didn't work.

The syntax looked good and I'm pretty certain this worked earlier, but
now the example was totally removed both on Read The Docs and in
locally generated version. After fighting it for some time I decided
it's easiest to just remove highlighting altogether.
Process: Enhance docs about passing arguments. Fixes #1861.