Fixing bug in write_element_values() where wrong number of vars was computed.
Use mesh.n_elem() instead of whatever the Exodus writer has for num_elem.
Add fparser auto-differentiation module
add abs(), log2() and log10()
more trig funcs and decompose some multiops
being more explicit about Value_t, cleanup, add opcodes
Protect undefined symbols (cNop) when optimizer is disabled

start work on cFetch
add float based instantiation
add cRSqrt and cCbrt, rm cLog2by
add helper function to test if function is == 0
Rm debug output, send errors to cerr.
Fixing a few typos before final merge.
Merge branch 'autodiff'
Merge pull request #246 from libMesh/exodus_fix

Fixing bug in write_element_values() where wrong number of vars was computed
Construct single-precision vectors in one line.
Add switch to enable debugging functions in fparser (Closes #247)
Merge pull request #247 from dschwen/fparser_debug

add switch to enable debugging functions in fparser