Ffc

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- Nothing changed yet

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- Let ffc -O parameter take an optional integer level like -O2, -O0
- Implement blockwise optimizations in uflacs code generation
- Expose uflacs optimization parameters through parameter system

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- Jit compiler now compiles elements separately from forms to avoid duplicate work
- Add parameter max_signature_length to optionally shorten signatures in the jit cache
- Move uflacs module into ffc.uflacs
- Remove installation of pkg-config and CMake files (UFC path and
compiler flags are available from ffc module)
- Add dependency on dijitso and remove dependency on instant
- Add experimental Bitbucket pipelines
- Tidy the repo after UFC and UFLACS merge, and general spring cleanup. This
includes removal of instructions how to merge two repos, commit hash
c8389032268041fe94682790cb773663bdf27286.

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- Add function get_ufc_include to get path to ufc.h
- Merge UFLACS into FFC
- Generalize ufc interface to non-affine parameterized coordinates
- Add ufc::coordinate_mapping class
- Make ufc interface depend on C++11 features requiring gcc version >= 4.8
- Add function ufc_signature() to the form compiler interface
- Add function git_commit_hash()

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- Use std::vector<std::vector<std::size_t> > for topology data
- Remove vertex coordinates from ufc::cell
- Improve detection of compatible Python libraries
- Add current swigversion to the JIT compiled extension module
- Remove dofmap::max_local_dimension()
- Remove cell argument from dofmap::local_dimension()

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- Add new class ufc::point_integral
- Use CMake to configure JIT compilation of forms
- Generate UseUFC.cmake during configuration
- Remove init_mesh(), init_cell(), init_mesh_finalize()
- Remove ufc::mesh and add a vector of num_mesh_entities to global_dimension() and tabulate_dofs().