parse: add support for presets

Add new parse syntax: @preset="<preset-name>" to load presets.
Fixes #86
27 jobs for launch_presets in 176 minutes and 14 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Preparation
passed #968784
gst indent

00:00:31

passed #968783
manifest

00:00:36

 
  Build
passed #968794
build cerbero cross-android universal

00:12:02

manual #968798
gst-ios-12.2 allowed to fail manual
build cerbero cross-ios universal
passed #968795
build cerbero cross win32

00:06:02

passed #968796
build cerbero cross win64

00:07:07

passed #968793
build cerbero fedora x86_64

00:05:27

passed #968797
gst-macos-10.14
build cerbero macos x86_64

00:09:00

passed #968789
build clang fedora x86_64

00:06:25

passed #968785
build fedora x86_64

00:06:20

passed #968792
docker windows 1607
build msys2

00:14:48

passed #968786
build nodebug fedora x86_64

00:04:30

passed #968787
build static fedora x86_64

00:14:22

passed #968788
build static nodebug fedora x86_64

00:03:27

passed #968790
docker windows 1607
build vs2017 amd64

00:14:09

passed #968791
docker windows 1607
build vs2017 x86

00:13:42

 
  Test
passed #968799
gstreamer
check fedora

00:03:58

failed #968800
gstreamer
integration testsuites fedora

00:39:59

passed #968805
gstreamer
valgrind bad

00:06:40

passed #968802
gstreamer
valgrind base

00:10:17

passed #968801
gstreamer
valgrind core

00:11:59

passed #968806
gstreamer
valgrind ges

00:06:57

passed #968803
gstreamer
valgrind good

00:08:07

failed #968804
gstreamer
valgrind ugly

00:02:05

 
  Integrate
passed #968807
cross-android universal examples

00:07:16

skipped #968809
gst-ios-12.2 allowed to fail manual
cross-ios universal examples
passed #968808
documentation

00:02:58

 
Name Stage Failure
failed
valgrind ugly Test
!! Could not derive your terminal width !!
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 33 matching files

Uploading artifacts to coordinator... ok
id=968804 responseStatus=201 Created token=qc9oxe2b
Uploading artifacts...
validate-logs/*.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=968804 responseStatus=201 Created token=qc9oxe2b
ERROR: Job failed: exit code 1
failed
integration testsuites fedora Test
!! Could not derive your terminal width !!
Uploading artifacts...
gst-build/build/meson-logs/: found 2 matching files
validate-logs: found 69867 matching files

Uploading artifacts to coordinator... ok
id=968800 responseStatus=201 Created token=6vSFzRQE
Uploading artifacts...
validate-logs/*.xml: found 1 matching files

Uploading artifacts to coordinator... ok
id=968800 responseStatus=201 Created token=6vSFzRQE
ERROR: Job failed: exit code 1