Updated House of Representatives 2018

[servo75 30]

I've made some updates to the 2018 House of Representatives campaign on the Campaigns page.

1. Updated incumbents
    Added special election winners
    Updated committee chairs
    Input some newly-declared challengers
2. MAGA Party
    Challenging moderate/liberal Republicans
    On ballot in districts where...
    Trump carried by 20+ points and either Democrat incumbent or GOP under 80% by Heritage Scorecard
3. "TBD" in districts where GOP/Dem has targeted but no formal declared candidates.  Non-targeted districts are "off ballot" if no one has declared.

4. If DCCC or RNCC has a district in a "frontline program" for extra support (source ballotpedia), I raised Candidate Strength by 1

5. Region percentages:
    GOP% = 50 + Cook PVI + Cook Prediction *

*Cook Prediction:
Likely GOP    +8
Lean GOP    +5
Tossup GOP    +1
Tossup Dem    -1
Lean Dem    -5
Likely Dem    -8