Escaping is right, but "raw" context entry type does not de-serialise, so
deadlock debugger password was stored in an unintended format. Moving
deadlock_debugger_password to a buildout section involves required magic.
Move other parameters for consistency.
Also, honour deadlock_path parameter, which was previously ignored.

Do not expose a parameter, as index can be reconstructed from data anyway.
Rotating is anyway needed as index backup can take a significant amount of
space for rare practical use.
Also, remove this point from TODO.

Balancer parameters were and are not supported, so this compatibility
breakage is not important.
The goal of this change is to make balancer parameter layout consistent
with other software-types.
Also, balancer's base TCP port is not taken from empty-string parameter
anymore.

They contain section references, not immediate values, so they are intended
to be evaluated by buildout and hence must not be escaped.

Not perfect yet, as some strings end in configuration files for example
and need escape mechanisms aware of individual configuration file syntaxes.

no need to specify 'python = ${buildout:python}' because it is the default behaviour.

in python 2.5 or later, we can import from xml.etree.cElementTree instead.