extended SendBuffer with low level memory functions

See merge request !21

Fixed a bug related improperly passing through parse_symtab call when extended U…

See merge request !18

Resolve "loadBlockData/saveBlockData not working for pe"

Closes #19

See merge request !19

Fixed a bug related improperly passing through parse_symtab call when extended USR is called recursively.

Fixed problem related to case-sensitivity of locally defined variables
Fixed problem related to compilation with latest version of clang (version 5.0.0 trunk 303036)
Minor code cleanup

move mpi stubs into walberla::mpistubs namespace

Closes #18

See merge request !17

Replaces exception thrown on getBlock with NULL

See merge request !12

Adding special documentation for modules (pe)

See merge request !14

New PE Body: Union

See merge request !4

WALBERLA_CHECK_FLOAT_EQUAL_EPSILON
WALBERLA_CHECK_FLOAT_UNEQUAL_EPSILON
WALBERLA_ASSERT_FLOAT_EQUAL_EPSILON
WALBERLA_ASSERT_FLOAT_UNEQUAL_EPSILON

Change Box to Capsule in rigidbody communication header

See merge request !13

getMaximumPenetration()
getNumberOfContacts()
getNumberOfContactsTreated()

two versions available now via CMake switch:
   - by default the Python module is built without LBM module, since
     lbmpy can be used for this. Reduces compile time substantially.
   - if the LBM is needed in python, for example for the lbmpy testsuite
     it can be included by setting the CMake switch
     WALBERLA_BUILD_WITH_PYTHON_LBM

- Bug occurred if a BufferSystem (or communication scheme) was copied
  and the first object went out of scope.
- Internally a pointer was kept which was still pointing to the original
  BufferSystem

Fixes #16

Merge branch '17-does-not-compile-error-cannot-convert-walberla-real_t-aka-double-to-real_t-aka-float' into 'master'

Resolve "Does not compile: error: cannot convert ‘walberla::real_t* {aka double*}’ to ‘real_t* {aka float*}’"

Closes #17

See merge request !9