more configurability, cleanup and fixes

[betaboon]

• Please check if the PR fulfills these requirements

• [ ] The commit message follows our guidelines

• [ ] Docs have been added / updated in README.md (for features)

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)

  • feature
  • bugfix
  • docs update

• What is the current behavior? (You can also link to an open issue here)

• What is the new behavior (if this is a feature change)?

  • fine grained configuration options
  • module svn: FIX wrong symbol
  • section vcs: cleanup whitespaces
  • section exit: padding around exit-code

• Does this PR introduce a breaking change? (What changes might users need to make in their configuration due to this PR?)

  • configuration options are changed
  • syntax for color-schemes changed

• Other information:

[betaboon]

i have only adapted the gruvbox-theme to these proposed changes. If you would like to accept these changes i would have to adapt the remaining themes to the new syntax first.

[betaboon]

@eendroroy just added the rest of the adapted themes and added a new option ALIEN_SECTION_PATH_COMPONENTS