Change default minimum intensity value and add support for 0=all blocks to median ratio normalizer

[Jari Häkkinen]

In BASE2 plugin 'Normalization: Median ratio', parameter Blockgroup size can not be set to 0 (must be 1 or larger).

This should be changed so that Blockgroup size = 0 = use all blocks as a single group (just as it works in BASE2 plugin 'Normalization: Lowess').

Ideally, setting Blockgroup size = 0 should enable the plugin to run irrespectively of whether block information is available for bioassays. Such as in the case where connection to rawdata table is lost, e.g., after running BASE1 plug-in virtual array.

Also, the default value for Minimum intensity should be changed to 0 since it behaves like a filter. The default value should keep all data.

[Nicklas Nordborg]

(In [5103]) Fixes #1379: Change default minimum intensity value and add support for 0=all blocks to median ratio normalizer