Interface data storage in PROGMEM (#71)

Adds a webpack plugin to package interface as PROGMEM into a header file in the framework.
Adds a build flag to optionally enable serving from PROGMEM or SPIFFS as required
Adds documentation changes to describe changes

scripts/build_interface.py

@@ -0,0 +1,36 @@
+from pathlib import Path
+from shutil import copytree
+from shutil import rmtree
+from subprocess import check_output, Popen, PIPE, STDOUT, CalledProcessError
+from os import chdir
+
+Import("env")
+
+def flagExists(flag):
+    buildFlags = env.ParseFlags(env["BUILD_FLAGS"])
+    for define in buildFlags.get("CPPDEFINES"):
+        if (define == flag or (isinstance(define, list) and define[0] == flag)):
+            return True
+
+def buildWeb():
+    chdir("interface")
+    print("Building interface with npm")
+    try:
+        env.Execute("npm install")
+        env.Execute("npm run build")
+        buildPath = Path("build")
+        wwwPath = Path("../data/www")
+        if wwwPath.exists() and wwwPath.is_dir():
+            rmtree(wwwPath)        
+        if not flagExists("PROGMEM_WWW"):
+            print("Copying interface to data directory")
+            copytree(buildPath, wwwPath)
+    finally:
+        chdir("..")
+
+if (len(BUILD_TARGETS) == 0 or "upload" in BUILD_TARGETS):
+    buildWeb()
+else:
+    print("Skipping build interface step for target(s): " + ", ".join(BUILD_TARGETS))
+
+

scripts/timelib_fix.py

@@ -0,0 +1,40 @@
+import os
+import sys
+import re
+
+Import("env")
+
+# Find files under 'root' of a given 'fileName' in directories matching 'subDirectoryPattern'
+# This will allow us to safely find the offending Time.h file for removal prior to building
+def findSubDirectoryFiles(root, subDirectoryPattern, fileName):
+    subDirectories = os.listdir(root)
+    subDirectories = filter(lambda d: re.match(subDirectoryPattern, d), subDirectories)  
+    result = []
+    for subDirectory in subDirectories:
+        candidateFile = os.path.join(root, subDirectory, fileName)
+        if os.path.isfile(candidateFile):
+            result.append(candidateFile)
+    return result
+
+def deleteTimeHeader(libDepsDir):
+    timeHeaderFile = "Time.h"
+    timeLibDirectoryPattern = "Time(_ID[0-9]+)?"
+
+    # delete the file, as long as we only find one
+    if os.path.isdir(libDepsDir) :
+        deletionCandidates = findSubDirectoryFiles(libDepsDir, timeLibDirectoryPattern, timeHeaderFile)
+        numDeletionCandidates = len(deletionCandidates)
+        if numDeletionCandidates == 1:
+            os.remove(deletionCandidates[0])
+        elif numDeletionCandidates > 1:        
+            os.write(2, "Can\'t delete Time.h, more than one instance found:\n" + "\n".join(deletionCandidates))
+            sys.exit(1)
+
+# old lib deps directory
+deleteTimeHeader(os.path.join(env.subst("$PROJECT_DIR"), ".piolibdeps"))
+
+# pre 4.x lib deps directory
+deleteTimeHeader(os.path.join(env.subst("$PROJECTLIBDEPS_DIR"), env.subst("$PIOENV")))
+
+# >4.x lib deps directory
+deleteTimeHeader(os.path.join(env.subst("$PROJECT_LIBDEPS_DIR"), env.subst("$PIOENV")))