[cs] Typos and formulation changes in Ch. 1 up to 1.3 included.
Merge branch 'master' of https://github.com/progit/progit.git
[cs] changes to Chapter 1, section 1.4
[it] updating chapter6

Reviewed "A SHORT NOTE ABOUT SHA-1"
[nl] Synchronized translation with SHA-1 3c18779
Merge pull request #742 from Cpt-xx/synchVersions

[nl] Synchronized translation with SHA-1 3c18779
update `git reflog` output to current one
[it] fix error in formating
[it] fix remaining typos
[it] fix space at end of title
switch travis to parallel ci check
travis: add e-mail notification on status change
Apply 60e2618 to ja tree
Apply c418e2e to ja tree
Apply 44936fd to ja tree
Apply 3f6c105 to ja tree
[nl] Synchronized translation with SHA-1 3c18779
[it] reviewing chapter 6

reviewed "Branch References"
[it] reviewing chapter 6

reviewed "RefLog Shortnames"
[it] reviewing chapter 6

reviewed "Ancestry References"