Update and reorganise themes (#893)

* Drop the subfolders for GUI themes
* Remove bundled font support
* Add safe file read function
* Allow loading themes from multiple locations
* Clean up unused variables
* Clean up icons class
* Merge icon theme icons
* Update icon theme class
* Remove guiDark config setting
* Fix tests
* Fix handling of default theme
* Update icon readmes
* Add test for getGuiItem common function

novelwriter/common.py

@@ -23,6 +23,7 @@ You should have received a copy of the GNU General Public License
 along with this program. If not, see <https://www.gnu.org/licenses/>.
 """
 
+import os
 import json
 import hashlib
 import logging
@@ -415,6 +416,24 @@ def jsonEncode(data, n=0, nmax=0):
 #  File and File System Functions
 # =============================================================================================== #
 
+def readTextFile(filePath):
+    """Read the content of a text file in a robust manner.
+    """
+    if not os.path.isfile(filePath):
+        return ""
+
+    fileText = ""
+    try:
+        with open(filePath, mode="r", encoding="utf-8") as inFile:
+            fileText = inFile.read()
+    except Exception:
+        logger.error("Could not read file: %s", filePath)
+        logException()
+        return ""
+
+    return fileText
+
+
 def makeFileNameSafe(theText):
     """Returns a filename safe version of the text.
     """