fix #7111, tab completion where the first item is ""

also use start() instead of 1
fix common_prefix on unicode strings
add complex polygamma and Hurwitz zeta functions (fixes #7033)
use next instead of nextind
Improved sparse getindex

Now faster and uses less memory in most common cases.
fixed type-stability of chorner and polygamma (workaround for #7060)
NEWS update for polygamma
Change default .travis.yml file to prevent Travis from doing a shallow clone for new packages. Fixes #5222.
Merge pull request #7136 from quinnj/jq/travis

Default .travis.yml changes
Merge pull request #7121 from JuliaLang/jb/7111

fix #7111, tab completion where the first item is ""
Merge pull request #7131 from mauro3/sparse_indexing2

Improved sparse getindex
Use '-t' option in git checkout to set upstream tracking on branches. Fixes #5476.
Merge pull request #7125 from stevengj/polygamma

RFC: add complex polygamma and Hurwitz zeta functions
update doc for Timer
document division error behavior
Fix printing of commas in Dict showcompact
bugfix in zeta(s,z) for complex s and real z
simpler version of fix from commit f70673f60ea11074a3763379eab936d72f451c24
Merge pull request #7144 from mbauman/fixshowcompact

Fix printing of commas in Dict showcompact
Merge pull request #7138 from quinnj/jq/checkout

Add '-t' option to git checkout