Bugfixes and PEP-8 style fixes in SVMClassifier

SVMClassifier's docstring erroniously reports that it is running a "C"-type SVM.  Instead, the `SVMType` field of the properties dictionary maps to a "NU" value, causing a KernelException on the `Orange` side.

This pull-request patches the above error and improves the docstring for SVMClassifier, which previously did not mention that structure of the `properties` dict.  It also turns the `SVMClassifier` class into a new-style class by inheriting from `object`.

This pull-request also fixes a large number of style errors including:

- C-style if-statements (parentheses surrounding the conditional statements)
- String concatenation using the `+` operator (replaced with `str.join`)
- index-driven iteration (replaced with iterators)
- Long lines (most lines > 79 characters were broken up)
- Minor typos and spacing problems