data-lens is not a dep of idris

lens is, but that isn't available in the binary repos of the old version
of Ubuntu Travis-CI runs.
Set the handles used for --client to use UTF-8

Previously they were binary-mode, so they used char8 “encoding”, taking
codepoint values modulo 256, leading to cryptic identifier mangling errors
when using idris-vim.
suc{Max,Min}{L,R} + add mrb to CONTRIBUTORS
Fix typo in Idris network C code
Correctly count applications of variables in :search
add system to Effects.System as is
add system to Effects/System neweffects
Add goal types to quasiquotes.

A quasiquote expression can be given a goal type for the elaborator,
which helps with disambiguation. For instance, `(() : ()) quotes the
unit constructor, while `(() : Type) quotes the unit type.  Both goal
types and quasiquote are typechecked in the global environment.
Merge pull request #1348 from david-christiansen/quasiquote

Add goal types to quasiquotes.
Merge pull request #1346 from bmsherman/searchVarMatching

Correctly count applications of variables in :search
Merge pull request #1344 from mrb/maximum_succ_proof

suc{Max,Min}{L,R} + add mrb to CONTRIBUTORS
javascript: simple dead code elimination
Merge pull request #1349 from raichoo/javascript

javascript: simple dead code elimination
Predicates for Prelude Strings
Merge pull request #1229 from LeifW/travis_deps

Don't bother installing data-lens
Merge pull request #1334 from Melvar/fix-ipc-enc

Set the handles used for --client to use UTF-8
Merge pull request #1336 from Heather/system

add system to Effects.System as is
Merge pull request #1345 from bmsherman/idrisNetFix

Fix typo in Idris network C code
Merge pull request #1352 from Heather/string

Predicates for Prelude Strings
Preliminary support for a :let command in the repl