SciDAVis - Improvements SVN-temp

- fixed bug 2572142: Error bars connection line incorrect for small errors

- Removing unused alex_b branch.

- fixed bug 2520366: Differentiation does not work anymore

- improved auto-detection of Python lib on Windows
- removed usage of gsl_stats_tss and gsl_stats_wtss
in order to remain compatible with GSL 1.8 (latest GnuWin32 release)

Added auto-detection of SIP includepath (previously was assumed to be identical to Python includepath).

Merged all missing bug fixes from current_stable.

Fixed bug #2099820 (Missing color indicators in PDF export)

Fixed constant fit parameters (naive string substitution fails if a parameter
name is a substring of something else, e.g. another parameter name).

This is a rather large patch for a bug-fix release, but there doesn't seem to
be an easy fix. Unfortunately, fast muParser-provided numerical differentiation
doesn't work with this ansatz, so non-linear fitting with user-defined
functions gets noticably slower.

- Fixed bug #1983861 (comments not shown after opening)
- Fixed some problems with exporting legends at high resolutions. Hard-coded
line width of border is still an issue, though.
- Fixed inward tick marks.
- Fixed graph layer cloning (auto-scaling fonts property wasn't copied).

- fixed a bug in AxesDialog that cause text based axes
to be set to numeric (this is probably related
to the second part in bug #2231471)