bump version to v1.15.1.0dev
use SHLIB_EXT for all GMP easyconfigs

Signed-off-by: Fotis Georgatos <fotis.georgatos@uni.lu>
use SHLIB_EXT for all MPFR easyconfigs

Signed-off-by: Fotis Georgatos <fotis.georgatos@uni.lu>
fix TopHat homepage and source_urls since page moved
bump version to v1.15.1.0 and update release notes
fix versions in release notes
make iomkl toolchain compatible with HierarchicalMNS
fix remark
add missing entry in release notes
Merge branch 'v1.15.x'