Merge pull request #209 from DrylandEcology/bugfix_206

- adjustments so that the clang compiler works
- set submodule googletest to specific commit
- specify specific warnings in the makefile to be ignored (instead of propagated to errors)
- more consistent CI across compilers on `travis`

.gitmodules

@@ -1,3 +1,4 @@
 [submodule "googletest"]
 	path = googletest
 	url = https://github.com/google/googletest
+	branch = master

.travis.yml

@@ -1,12 +1,13 @@
-language: c
+language: cpp
+
 compiler:
   - clang
   - gcc
 
 script:
   - export CPPFLAGS=-DSWDEBUG && make cleaner bint_run
   - make cleaner cov test_run
-  - make cleaner
 
 after_success:
   - bash <(curl -s https://codecov.io/bash) || echo "Codecov did not collect coverage reports"
+  - make cleaner

README.md

@@ -15,6 +15,7 @@
 [11]: https://img.shields.io/github/downloads/DrylandEcology/SOILWAT2/total.svg
 [12]: https://github.com/DrylandEcology/SOILWAT2
 
+<br>
 
 # SOILWAT2
 
@@ -38,6 +39,7 @@ Some recent references
 * Schlaepfer, D. R., W. K. Lauenroth, and J. B. Bradford. 2012. Ecohydrological
   niche of sagebrush ecosystems. Ecohydrology 5:453-466.
 
+<br>
 
 ## How to contribute
 You can help us in different ways:
@@ -68,7 +70,9 @@ __Tests, documentation, and code__ form a trinity
     but don't push them to the repository
 - Code tests
   * Use [GoogleTest](https://github.com/google/googletest/blob/master/googletest/docs/Documentation.md)
-    to add unit tests to the existing framework
+    to add unit tests to the existing framework in the folder `test/` where
+    each unit test file uses the naming scheme `test/test_*.cc`.
+  * Note: `SOILWAT2` is written in C whereas `GoogleTest` is a C++ framework.
   * Run unit tests locally on the command-line with
     ```
     make test     # compiles the unit-test binary/executable (with `-DSWDEBUG`)
@@ -116,13 +120,19 @@ __Tests, documentation, and code__ form a trinity
     ```
     make cleaner bint_run CPPFLAGS=-DSWDEBUG
     ```
-  * The "makefile" also contains pre-configured debugging targets including
-    `bin_debug`, `bind`, and `bind_valgrind` (see description in `makefile`).
-    If **valgrind** is installed, then for example
+  * Alternatively, you can use the pre-configured debugging targets
+    `bin_debug` and `bind`, for instance, with
+    ```
+    make cleaner bind bint_run
+    ```
+  * If **valgrind** is installed, then you can call the target `bind_valgrind`
+    (see description in `makefile`) with
     ```
     make cleaner bind_valgrind
     ```
 
+<br>
+
 ## Notes
 
 __Version numbers__