Explicitely accept any SizedData where possible in ImageRaster and BintableColumns

[kabasset]

Methods like:

void ImageRaster::readTo(TRaster& raster)
void BintableColumns::readTo(ColumnKey key, TColumn& column)

(should) only use TRaster/TColumn::value_type, raster/column.size() and raster/column.data() (to be checked) so that the declaration and doc could be changed to:

void ImageRaster::readTo(TContainer& container)
void BintableColumns::readTo(ColumnKey key, TContainer& container)

without even changing the definition!

This would explicitly allow bypassing Raster and Column, e.g.:

// Given: ImageRaster du
std::vector<float> raster(du.readSize());
du.readTo(raster);

// Given: BintableColumns du
std::vector<float> column(du.readRowCount());
du.readTo("NAME", column);

[kabasset]

Check after #32 is closed