* 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

* initial ldscripts refactoring

* add missing menu options

* board for 2.3.0 and 2.4.2

* test with core 2.5.0

* typo

* ...same typo in other boards.local.txt

* generate boards.local.txt from common template

* Depend on file presence instead of platform version

* sdk selection

* Override only relevant entries

* generate ldscripts

* formatting

* unused

* fix section scope

* fix linker script comment and build getting stuck

* py2 compat

platformio from pip still does not support py3

* add TODO for py3

* chmod +x, remove leading newline

* comment with real spiffs size

* fixup! chmod +x, remove leading newline

* regenerate all ldscripts

* Preventive fix of spiffs_end calculation

* update arg parsing

* generate only 2.3.0 and latest

* readme for boards.local.txt

* Update ldscript readme

* unique flash sizes

* fix sub

* line break

* correct way to get framework path

* Alias for _FS_... symbols

* unused 2m1m1s

* bump?

* show travis logs

* ensure latest toolchain for travis

* check platform packages when building

- update file paths: .pioenvs -> .pio/build, .piolibdeps -> .pio/libdeps
- modify envs to use common settings
- enable shared libs in travis and ota scripts

Bump npm version installed by travis
Update package-lock for latest npm version
Bump packages versions and clean-up unused
Missing datatables.js images to avoid warnings

Travis pulls tag as branch, so 'branch = master' is never true.
Use same regexp as earlier build.sh did

- Revert test to being serial. Releases are using parallel jobs.
- Some cosmetic changes in build.sh