Adding an extra API functionality to use the local DOF to assemble vectors and matrices.

- This should generally be faster than using VecSetValues. Use DMMoabGetLocalFieldDofs for these operations.
- Should work with MatSetValuesLocal, VecSetValuesLocal also (untested).
A verified, parallel, debug version of the poisson solver based on DMMoab API and FEM assembly. Solution is consistent and gives verifiable results in serial and parallel. Can also use LOCAL_ASSEMBLY to do two different types of vector RHS assembly.
Adding several important public API functions to DMMoab and few fixes.

a3b7357: Add interface functions to get the global, local and ghosted vertex distributions of the DM.
7478aaf:
  1) DMMoabSetGlobalFieldVector - Use when the number of fields > 1 and want to assign a single global solution vector to be split in terms of tag arrays.
  2) DMMoabGetDofs - Local/Blocked variants to get the individual field-independent vertex GID numbering. This is useful for traversals based on nodes directly. Used in FD-type computations.
  3) Some minor bug fixes.
Fully revamping the 1-D Brusselator solver based on DMMoab new API specification. Verified in serial.
Make sure the nfields is initialized during creation. Added some error checks.
Fix a bug in nonzero pattern when bs>1. Also remove the redundant gindices since we store this data in dmmoab.
Adding a GetDimension API method.
Initial modifications to allow vertex based traversals and miscellaneous bug-fixes.

1) Adding API functions for getting vertex-connectivity for FD type calculations and DOF-maps etc.
2) Fix bugs in memory allocations in most of the Field/Block/Local DOF calculation routines.
3) Add PetscBool arrays to store whether the entities are on the boundary. This makes the query for boundary vertices and elements a simple look-up during FEM/FD assembly.
4) Introducing DMMoabGetAllVertices to access both local+ghost vertices. This might not be entirely necessary for FD and can remove it in the future.
Some bug fixes for the ghosted exchange of tag data during Get/Restore Array for DMMoabVec
Adding several important public API functions to DMMoab and few fixes.

611d6c0: Removing the storage of boundary nodes, vertices and faces. Leaning up DMMoab. Only store markers instead.
f68869f: Fix some segfaults due to incorrect memory allocation for boundary data.
Fixing a MOAB output bug for parllel write.
A global field vector can optionally be passed to DM where the local field data are ripped out and serialized to file.
Making the poisson driver stable along with modifications on how the local assembly is performed.
Fix for the NNZ pattern computation when user asks for more layers of ghosted entities. The DMMoab itself does not care about these extra level of DOFs and only needs the interface(d837989). No need to override the user options from command line(b49477c4).
Cleaning up DMMoab and splitting the monolithic implementation into smaller files for organization based on field-management and io. Adding several variables to core DMMoab data structure to cache the necessary IDs for FEM-type assembly and traversals. Removed all references to Section since profiling indicated that this was slow overall.
Feature additions and fixes. 1) Making the fileset by default represent root set. Useful when user handles the creation of mesh etc. 2) Renumber all entities after resolving shared nodes.
Fixing a bug in DMMoabSetLocalVertices and rearranging the DMSetUp method to allow for user setting the range of vertices separately where DM is explicitly defined on.
Makefile modifications to compile dmmbfield and dmmbio.
Adding the first draft capability to allow both MOAB and native Vec with DMMoab. Also setting the necessary Mapping data so that SetLocal and SetBlockedLocal can be used.
Necessary changes to examples and tests.

d6f5831: Modifying ex4.c to the new interface changes.
c084c7f: Fix example 1 to use the new interface.
da41520: Several changes to the 1-d ex2.cxx driver. Trying out different methods of assembling the FEM operators since the default idea seems to be about 2 times slower than DMDA assembly.