Core 2.6.0+ fixes (#1852)

* Core 2.6.0+ fixes

* fix env -> config, run travis04 job

* don't duplicate free heap in frag data, use single stats struct

* fix dtostrf warnings, bump buffer sizes

* ...and even less words for fragmentation stat

code/extra_script_pre.py

@@ -8,6 +8,7 @@ import sys
 
 TRAVIS = os.environ.get("TRAVIS")
 PIO_PLATFORM = env.PioPlatform()
+CONFIG = env.GetProjectConfig()
 
 
 class ExtraScriptError(Exception):
@@ -50,12 +51,11 @@ def library_manager_libdeps(lib_deps, storage=None):
 
 
 def get_shared_libdeps_dir(section, name):
-    cfg = env.GetProjectConfig()
 
-    if not cfg.has_option(section, name):
+    if not CONFIG.has_option(section, name):
         raise ExtraScriptError("{}.{} is required to be set".format(section, name))
 
-    opt = cfg.get(section, name)
+    opt = CONFIG.get(section, name)
 
     if not opt in env.GetProjectOption("lib_extra_dirs"):
         raise ExtraScriptError(
@@ -73,10 +73,10 @@ def ensure_platform_updated():
     except Exception:
         print("Warning: no connection, cannot check for outdated packages", file=sys.stderr)
 
-
 # latest toolchain is still optional with PIO (TODO: recheck after 2.6.0!)
-ensure_platform_updated()
-
+# also updates arduino core git to the latest master commit
+if TRAVIS and (env.GetProjectOption("platform") == CONFIG.get("common", "arduino_core_git")):
+    ensure_platform_updated()
 
 # to speed-up build process, install libraries in either global or local shared storage
 if os.environ.get("ESPURNA_PIO_SHARED_LIBRARIES"):