Generator: Fixed GEMM issue
CMake: Fixes of quotation marks for list variables.

CMake variables which are already a list should not be put in double quotes.
Fixes a7e491f8d5a520d733dcbc6f7c8ae1f635c43f6b and issue #63.
Core: Moved some constructors from matrix.hpp to matrix_def.hpp

Could cause some linkage issue when matrix_proxy.hpp was included but not matrix.hpp
Doxygen: Updated documentation of examples and tests for full HTML-manual integration.

Requires Doxygen 1.8.x or above.
Matrix: Use memory_write() instead of memory_create() whenever possible.

If a user has provided her own memory buffers, the use of copy() to update
the matrix should reside in the same user-provided buffer and not create a new one.
Also, memory_write() is usually faster than memory_create().
Fixes #77.
Sparse matrices: Added clear() member function.

This way a user can conveniently free memory. Resolves #98.
Matrix, Vector: Passing host scalars of different numerical type for expressions again possible.

Resolves #71.
Matrix: Fixed assertion check in fast_copy().

Resulted in a conversion warning and in a nightly test failure.
Matrix: Fixed remaining issues with providing numerical factors of different scalar types.

Supplements 80697cf13dc2c80bdb676a233766281e678ac276 and addresses #71.
Vector: Added support for resizing a vector<T> object with copy if it has zero size.

The following is now legitimate:
  std::vector<T> x(N);
  viennacl::vector<T> vcl_x;
  viennacl::copy(x, vcl_x);
and resizes the ViennaCL vector accordingly (in the default context).
A similar support for the iterator interface is not possible without substantial refactoring.
Tests: Extended coverage of external linkage tests.
Bisect: Better compatibility with weaker hardware, macros guarded.

The default local workgroup size is now 128, providing better compatibility with
weaker and older hardware. Also, preprocessor defines are properly guarded with a
VIENNACL-prefix.
Clang 3.0: Fixed compilation problems with new copy() overload for vector.

Issue introduced with a89695e58077a75bfe748f8b5b85b62092698061
Preprocessor: Namespace'd all macros.

Some macros have not been properly prefixed. Now every proprocessor macro carries
a prefix 'VIENNACL_'.
OpenCL: Improved architecture detection for NVIDIA GPUs.

Older devices such as a GeForce 8600 GT have been mapped incorrectly.
The new detection fixes this for the devices currently available.
Needs to be revisited once the post-Maxwell generation is out.
Device-DB: Added GeForce GTX 580.
Device: Fixed architecture detection for Tesla GPUs.
Device-DB: Fixed collision of include guards for Fermi GPUs.
Device-DB: Added NVIDIA Tesla K20m.
Device: Minor tweaks and updates to detection of AMD architecture.