check that dummy params have one possible value
Static amd context holder

@neapel hope this compiles, don't have an amd device or amdfft to test.
amg_context is a template
Errors in vexcl/fft.h
Inlining fft_check_error

Required for use in several object files
Dropping Programs before Kernels is a memory leak
More compile time constants.
Merge remote-tracking branch 'neapel/master'
Reworked user function

The user function types are stateless again.
@neapel, I think the body construction in this variant is as dynamic as in
previous one. This should also be (probably negligibly) more effective, since
there are no values and only state information is used.
Enhance stencil oper definition

* Use same approach as with user-defined functions.
* Macro for type definition may be used if either function or stencil oper are
* used in several places in code (Because I suspect that locally defined
* structs have unique types even if definitions are identical).
doc update
doc update
Add cmake install rules for convenience of packaging
Fix typo documentaion->documentation
Add example source files to installation
Merge pull request #16 from raedwulf/install

CMake install targets
Merge branch 'master' of https://github.com/ddemidov/vexcl