New BC option: rot_sub_init for Temperature initalisation

Temperature is set at the left side and unset in the indenter footprint,
use to "pull" temperature from ther into indenter.

Also addition to elliptical dome surface: spherical shells of given
offset can be created.

Squashed commit of the following:

commit 01af6100baccbd389dca45e170c578cf642d73e7
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Tue Nov 11 11:42:49 2014 +0100

    Adding option not to set temperature at bottom

    Use for restart after sstemp

commit 3f0d2ab899ffba26030e56353b2c5a12beb550a4
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Fri Nov 7 16:18:42 2014 +0100

    Adding option domainfix and using old vex scaling

    domainfix will set velocity in entire domain 2 dz above indenter to 0
    returning to apply vex to osolve%z, since scaling the input parameters
    leads to different and incorrect shape of the indenter

commit 00a4fcd59cef94f7efc227f96297fa4d705bfce7
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Thu Nov 6 16:40:12 2014 +0100

    scaling input parameters with vex

    moving vex out of actual code and scaling input parameters at the start

commit 44171a3be6b1bc42eb4d80af3453bd6b3fa2e3cf
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Thu Nov 6 14:09:36 2014 +0100

    Changing Surface Calculation

    Trying a supposedly better spherical shell implementation

commit 1ee86ae001542ac5b37c7f41190b2d0cb913b8bd
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Thu Nov 6 11:12:51 2014 +0100

    Fixed geotherm calculation

commit 8ef7e3c3fe5e6631e4629cce003e4242c408b5bd
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Wed Nov 5 11:07:45 2014 +0100

    Added vex for geotherm calculation

commit 11e0f37f90b125014e254b3be9bab925b71590ef
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Wed Nov 5 10:44:29 2014 +0200

    Fixed typos, removed pi

    Pi defined by use constants, set comparison variables in if clauses to
    double precision

commit 15bb1a8e8fa9944d694f0f7fee2354ef8b3109d7
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Wed Nov 5 09:33:18 2014 +0100

    fixed minor typos

commit 9e9f1c7b9285f9497e4f1558179427520801eccf
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Tue Nov 4 10:30:49 2014 +0100

    Adding rot_sub_tinit for Temperature Initialisation

    New set of boundary conditions similar to rot_subduction, but with
    kfixt=1 at the left boundary and kfixt=0 within indenter footprint.
    Strictflow=True by default.

commit aa2fc2c179ca5b378995879c097bd92ce332b2c7
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Thu Oct 30 16:07:01 2014 +0100

    Added spherical shells description

commit 0c7c2532df3f0dd44c57e52a2c32a725b4cecc30
Author: Matthias Schmiddunser <matthias.schmiddunser@uni-tuebingen.de>
Date:   Thu Oct 30 16:02:47 2014 +0100

    Added spherical shells for indenter surface

    parallel surfaces of given distance to originally defined plane