fixes 10153: restore headings-color variable. fixes 10223: adds color to input addon. use direct-child selector more in table styles to better support nested tables

BS3 commits 794d7845199d46b89f45026d47091e6f30de73a2,
4b53ea52e9cc27ab27dde2695400fd6c95a0b6c2,
1e68143b39d51dcdbde575120628053c1e3ae966
Parameterize @breadcrumb-separator. fixes 10223: adds color to input addon. use direct-child selector more in table styles to better support nested tables

BS3 commits eb95574d8001591d1e056fcaeaf59138cbbb15a4,
4b53ea52e9cc27ab27dde2695400fd6c95a0b6c2,
1e68143b39d51dcdbde575120628053c1e3ae966
fixes 10136

BS3 commit 9e541fc717fdaa333bde760688dc6a16256e607d
Update index.html (update text from hero unit to jumbotron)

BS3 commit c9303c17abc0f2f0c488d2bdd3b1e8d3f8a56b10
remove unused link from navs section

BS3 commit 9616768659010979cd20f587791e966be38868d8
Getting started docs: tweaks to the _Basic template_ section. 'Getting started' section: refactoring for succinctness, active voice, and consistency with button and link captions. restore "only" wording in docs regarding Recess/less.js. Note the change to the progress bar. tweak 10298. fix straggler instance of "Tiny grid" terminology

BS3 commits 5c3614d97c869a6b928a50ffbdeb4e291aeaf53a,
8f80a76bf302c7724584da62a5851f1cce2cdb5d,
a7863c112d9b990d4da7a9c9052f58a42b855a02,
2066ea50a28119f3f890b84cabeb9214a346a1b5,
5418a7224346feaab6bf32a2fe9831d9a7a6d1b3,
93694898838b479d2806c53c827847f724312bcc
fixes 10153: restore headings-color variable. fixes 10223: adds color to input addon. fixes 10246: Use correct variable for link hover color in Customizer. finishes 10256 to add updated var to customizer; also fixes another old var

BS3 commits 794d7845199d46b89f45026d47091e6f30de73a2,
4b53ea52e9cc27ab27dde2695400fd6c95a0b6c2,
dfda3dfe3727fdd292d73cb7d9de5699527e3216,
58401daf1c6d97301af707045f8e1f0651e7290b