SciDAVis - Improvements SVN-temp

- Added support for hidding/showing 2D plot curves.
- Implemented saving/restoring of curve range and visibility. Still to be done for BoxPlots.

- Fixes some bugs and improves the CurveRangeDialog.

- Added files missing from the previous commit.
- Added support for opening Origin .ogw and .ogm files.

- Added support for plotting curves containing only a limited row range.
- Did a lot of reorganization to the code in Graph class, some functionality might be broken. Saving of curve ranges to project files is not implemented yet!

Fixed a bug and some typos.

- Fixed crashes during OPJ import owing to empty loose datasheets
- Added xErr & yErr column types import

- Fixes bug in bool Graph::focusNextPrevChild () function.

- Rewritten "IsBigEndian()" function in importOPJ class in a more portable way.
- Improved the import of tables horizontal header.
- Improved ExpDecayDialog and add/remove CurvesDialog.
- The resize of a text marker in a 2D plot now modifies the font of the text accordingly.
- Improved storing/restoring to/from files for the ImageMarker class.
- Fixed cloning of 2D plots.
- Improved exporting of plots to image format files.
- Fixed bugs due to mixing of QwtPlotCurve and QwtPlotItem in 2D plots.

- add matrix import from OPJ Files (v.7.5)

- added display of Delta_x/y in RangeSelectorTool