Performance index support: Reintroduced multiple index trees + implemented more commands.

It turned out that we need to keep a time series
of index trees for the performance index after all:
There will be one base index tree (at timestamp -1, i.e.
older than any result), and one index tree for the
timestamps where the current index tree was changed
(i.e. essentially one or more result histories and/or
sub-indexes added or removed).

The index is evaluated on the basis of
the closest index tree earlier than the requested
evaluation time. This ensures that the correct
history constants are used. (The history constants
in turn ensure continuity of the index values
upon adding or removing result histories and/or
sub-indexes).

The following bmclient commands are implemented so far:

- index set base    - sets the index base from an XML file
- index get tree    - lists a certain index tree as XML
- index get names   - lists the available index names
- index get values  - evaluates an index at a set of timestamps;
                      dumps the result to stdout
- index get plot    - same, except the result is plotted in an image
- get result        - verifies a result ID in the XML file

1 files changed, 0 insertions, 0 deletions

diff --git a/doc/er-diagram.dia b/doc/er-diagram.dia
index e9ee898..b434c30 100644
--- a/doc/er-diagram.dia
+++ b/doc/er-diagram.dia