Fix Makefile and update docs (#17)

* Fix dependency of FTDictionaryClass.o on Hash.o

* Update README with build information

* Rename default compiler to `gfortran`. Use `FC` for Fortran compiler variable in `Makefile` and `FCFLAGS` for Fortran compiler flags

* Change F90 to FC and switch back to FFLAGS

.github/workflows/ci.yml

@@ -61,7 +61,7 @@ jobs:
           ${{ matrix.compiler }} --version
       - name: Build
         run: |
-          make -j 2 F90=${{ matrix.compiler }}
+          make -j 2 FC=${{ matrix.compiler }}
       - name: Run tests
         run: |
           ./HOHQMesh -test
@@ -74,7 +74,7 @@ jobs:
         if: ${{ matrix.os == 'ubuntu-latest' }}
         run: |
           sudo apt-get install -y lcov
-          F90=${{ matrix.compiler }} ./Utilities/createcoverage
+          FC=${{ matrix.compiler }} ./Utilities/createcoverage
       - uses: codecov/codecov-action@v1
         if: ${{ matrix.os == 'ubuntu-latest' }}
         with:

Documentation/docs/releasing-a-new-version.md

@@ -81,10 +81,10 @@ tarball will fail!*
    current directory.
 5. Test the new release by executing
    ```bash
-   F90=gfortran ./Utilities/testrelease HOHQMesh-v1.3.0.tar.gz
+   FC=gfortran ./Utilities/testrelease HOHQMesh-v1.3.0.tar.gz
    ```
    Make sure you change the Fortran compiler executable to one suitable
-   for your system by modifying the `F90` environment variable accordingly.
+   for your system by modifying the `FC` environment variable accordingly.
    If it fails, do *not* just change the files in your current directory!
    Instead, figure out why the tests fail, fix them, commit and push the changes
    and start over.