blockforest: fix modernize-loop-convert, modernize-type-traits, modernize-return-braced-init-list, readability-delete-null-pointer

blockforest: fix modernize-avoid-c-arrays, performance-inefficient-vector-operation, modernize-loop-convert

Code quality improvements

See merge request !699

Update ExprTk to 0.0.3

See merge request !700

Merge kemmler/particle_coupling_GPU (particle coupling using code generation for PSM) into master

See merge request !696

Useful to design custom allocators.

Number formatting can be achieved with an imbued locale.

Address most occurrences of:
bugprone-unused-local-non-trivial-variable
bugprone-unhandled-self-assignment
bugprone-misplaced-widening-cast
bugprone-sizeof-expression
performance-for-range-copy
performance-faster-string-find
performance-inefficient-vector-operation
performance-noexcept-swap
misc-unused-using-decls
misc-header-include-cycle
misc-include-cleaner
readability-delete-null-pointer
readability-container-size-empty
readability-redundant-smartptr-get
readability-else-after-return

Fix memory alignment bug in PackInfo codegen

See merge request !698

Update lbmpy to 1.3.7

See merge request !697