constitution: count vacant seats when voting full reelection

The way the constitution is currently written, the SC can entirely
deadlock, if one seat is vacant and 50% of the remaining SC are calling
for no confidence, while the other 50% disagree.

The SC can neither be fully re-elected, nor make any other decisions
with simple majority.

Author: wolfgangwalther

doc/constitution.md

@@ -108,7 +108,7 @@ Deciding that an amendment is not substantial can be done by unanimity among a f
 
 #### Ordinary decisions
 
-Everything within the authority of SC that doesn't require an extraordinary decision can be decided with a simple majority (more than 50%) of a full SC (vacant seats count as abstaining).
+Everything within the authority of SC that doesn't require an extraordinary decision can be decided with a simple majority (more than 50%) of a full SC (vacant seats count as abstaining, except when voting for reelection).
 
 An exception to that is when there is when the [conflict of interest balance](#conflict-of-interest-coi-balance) condition is suspected to be violated.
 In that case, all non-involved currently serving SC members will have a simple majority decision over whether there is a violation.
@@ -205,6 +205,7 @@ A committee member elected in a special election will serve out the remainder of
 
 A simple majority within the SC may call a reelection of the entire SC based on perceived loss of confidence.
 In this case, it also has to be decided whether this election is considered a special election for the remainders of all the corresponding terms, or an initial election for full 2-year terms for half of the seats rounded up and 1-year half-terms for the remaining seats.
+Vacant seats vote in favour of reelection, and between initial election and special election they count towards special election.
 
 ### Removal for conduct