Fix overflow of 32-bit signed integers when multiplying two 32-bit integers: cast to 64-bit integers first, otherwise matrices with number of elements > 2^31 (e.g. a 48,000x48,000 custom kernel matrix) will not work.
Accidental file included
Clang will not take int64_t as an index into a vector, add [] for int64_t in SGVector
Need a third operator[]

Because the uint32_t used to index vectors elsewhere now cannot choose
between index_t and int64_t (before it only had the choice of
index_t=int32_t)
Other try to fix ambiguities: a single operator[] with int64_t
Simple intro for dimred notebook
Fix ordered list in INSTALL.md
added a few convienience methods and debug output
obtain from generic method
minor updates
added Gaussian mixture model notebook
Merge pull request #1737 from karlnapf/develop

GMM notebook
minor updates
Merge pull request #1738 from karlnapf/develop

minor updates to GMM notebook
Merge pull request #1736 from iglesias/feature/notebook/dimred

Simple intro for dimred notebook
Toy data generator for classification
Updated tapkee notebook
corrections of typos
Merge pull request #1740 from karlnapf/develop

corrections of typos
Merge pull request #1735 from van51/feature/data_gen

Toy data generator for classification