[build] Update version to v0.9.1

[build] Update version to v0.9.0

Merge pull request #2079 from ghaerr/v081

[build] Change version number to v0.8.1

Merge pull request #2037 from ghaerr/v080

Change version to v0.8.0

Merge pull request #1635 from ghaerr/070

[release] Update ELKS version number to v0.7.0

Merge pull request #1311 from ghaerr/060

[release] Increment version to 0.6.0

Merge pull request #1143 from ghaerr/version

Increment version to v0.5.0

Merge pull request #874 from ghaerr/version400

Increment version to 0.4.0

Release 0.3.0

Merge pull request #220 from mfld-fr/gnu

[kernel] Move to full GNU toolchain:
- Rewrite some assembly sources to ATT syntax
- Tune GCC options: small model, no relocations...
- Add LD scripts to output ELKS a.out
- Rework build scripts for full GNU
- Add RAW option for target image
- Warnings and glitches fixes
- Wipe out some BCC related stuff