ETV: Defined a separate variable for mean velocity instead of using wind[3] which was previously defined for Advection(2d) problems

EULER_VORTEX: periodicity for x and y directions added

Removed unused variables and In/OutFlow setup for EULER_VORTEX

examples/fluids/navierstokes.c: small fix in comments

EULER_VORTEX: all QFunctions are using same context

fluids/navierstokes: fix pointer semantics for Euler context

updated euler_vortex context

WIP: defined a new struct for euler_vortex

fix context in Euler_Sur QFunction

Update DMAddBoundary() call after change in API for euler-vortex problem

examples/fluids: added doc for euler traveling vortex test case

fixed context in euler_vortex test

removed computing current time in main function

current time added to User struct

fixed slip BCs on z direction

delete incorrect comments

add context for qf_rhsVol in euler_vortex

examples/fluids: add context for qf_rhsVol in EULER_VORTEX

WIP: added essential BCs

The physical in/outflow setup is removed and exact solutions are applied instead ... this commit needs to be reverted for a physical euler problem.

set the current time

some corrections

added forcing terms

fixed exact solutions

Added time to to the exact solution but needs to check the implementation