Delete src/SOLPS2IMAS.jl

File name changes are case-insensitive for macOS and thus git doesn't detect it unless you use `git config core.ignorecase false`. But doing that caused git to push `SOLPS2imas.jl` as new file instead of replacing `SOLPS2IMAS.jl`. Thus, I'm using Github browser gui to delete this file. Other people might require to change the file name manually or do a fresh clone.