Particle Methods:

[tsung1029]

In issue #40 I suggested adding methods for particles so we can allow for pushers such as

Vay
Higuera
Li
(and others?)

to be specified by PICMI. Today Jean Luc extended on this idea and say that particles methods should include pusher, charge deposition, and force interpolation. So I am proposing the following specificaitons for particles.

(1) pusher type (see above)

(2) particle shape (an integer for a spline order?)

(3) energy or momentum conserving force interpolation

(4) charge conservation (logical flag): is the charge deposition charge conserving? (full EM only)

I think that will cover all the EM PIC codes. Please feel free to comment here.