Add relion build script.

Builds from source based on git.

Currently only gcc/7.4.0 is used. Better performance is reported with
intel icc and MKL, but this would require additional openmpi variants.

Variants for 3.0.8 and 3.1-beta (780dd7b) are installed.

EM/relion/build

+#!/usr/bin/env modbuild
+
+pbuild::add_to_group 'EM'
+pbuild::use_cmake
+
+pbuild::prep() {
+
+    local BRANCH
+    if [[ "$V" =~ beta$ ]]; then
+        BRANCH="ver${V_MAJOR}.${V_MINOR}"
+    else
+        BRANCH="${V_PKG}"
+    fi
+
+    git clone --depth=1 -b "$BRANCH" https://github.com/3dem/relion.git "$SRC_DIR" || return $?
+}
+
+pbuild::pre_configure() {
+    pbuild::add_configure_args FORCE_OWN_FFTW=ON
+    pbuild::add_configure_args FORCE_OWN_FLTK=ON
+    pbuild::add_configure_args CUDA=ON
+    pbuild::add_configure_args CudaTexture=ON
+    pbuild::add_configure_args ALTCPU=ON
+    pbuild::add_configure_args FORCE_OWN_TBB=ON
+    # Requires intel compiler
+    #pbuild::add_configure_args MKLFFT=ON
+}
+

EM/relion/files/variants

+relion/2.1.b1	stable	gcc/4.9.4 openmpi/2.0.1 cuda/8.0.44
+relion/3.0_beta	stable	gcc/4.9.4 openmpi/2.0.1 cuda/8.0.44
+relion/3.0.8	unstable	gcc/7.4.0 openmpi/3.1.4_merlin6 cuda/9.2.148 b:cmake/3.14.0 b:tiff/4.0.9
+relion/3.1-beta	unstable	gcc/7.4.0 openmpi/3.1.4_merlin6 cuda/9.2.148 b:cmake/3.14.0 b:tiff/4.0.9
+

EM/relion/modulefile

+#%Module1.0
+
+module-whatis	        "3D reconstructions or 2D class averages in electron cryo-microscopy (cryo-EM)"
+module-url		"https://www2.mrc-lmb.cam.ac.uk/relion/index.php/Main_Page"
+module-license	        "GPLv2 license"
+module-maintainer	"Spencer Bliven <spencer.bliven@psi.ch>"
+
+module-help	"
+RELION (for REgularised LIkelihood OptimisatioN, pronounce rely-on) is a
+stand-alone computer program that employs an empirical Bayesian approach to
+refinement of (multiple) 3D reconstructions or 2D class averages in electron
+cryo-microscopy (cryo-EM). It is developed in the group of Sjors Scheres at the
+MRC Laboratory of Molecular Biology. Briefly, the ill-posed problem of
+3D-reconstruction is regularised by incorporating prior knowledge: the fact
+that macromolecular structures are smooth, i.e. they have limited power in the
+Fourier domain. In the corresponding Bayesian framework, many parameters of a
+statistical model are learned from the data, which leads to objective and
+high-quality results without the need for user expertise. The underlying theory
+is given in Scheres (2012) JMB. A more detailed description of its
+implementation is given in Scheres (2012) JSB. If RELION is useful in your
+work, please cite at least one of these papers. 
+
+Scheres(2012) JMB http://www.sciencedirect.com/science/article/pii/S0022283611012290
+Scheres(2012) JSB http://www.sciencedirect.com/science/article/pii/S1047847712002481
+"
+
+