Change regex to sanitize and normalize filenames passed to LiquidRenderer

[ashmaroli]

Motivation:

Currently, the resulting table from building with --profile has relative_path for files at the source dir but an absolute_path for files within a theme-gem (which can be a long string depending on the user's Ruby Installation location.)

Patch notes:

• all filenames are normalized to be relative to the source-directory or theme-root.
• if a path starts with a non-alphanumeric char, (e.g. ../../ or ~foo), those characters are ignored.
• no discernible effect on performance.

---

UPDATE - 09 FEB 2018

• prepend relative paths from theme-gem with the gem's dirname
  (e.g. minima-2.3.0/_includes/head.html)

[DirtyF]

current display when building with minima:

Filename                                              | Count |  Bytes |  Time
------------------------------------------------------+-------+--------+------
_posts/2018-01-22-welcome-to-jekyll.markdown          |     1 |  1.52K | 0.429
_layouts/default.html                                 |     4 | 20.80K | 0.095
_includes/head.html                                   |     4 |  7.25K | 0.056
_includes/footer.html                                 |     4 |  3.82K | 0.019
feed.xml                                              |     1 |  3.62K | 0.019
_includes/header.html                                 |     4 |  5.38K | 0.015
_includes/social.html                                 |     4 |  0.27K | 0.013
_layouts/post.html                                    |     1 |  2.20K | 0.003
_layouts/home.html                                    |     1 |  0.44K | 0.001
_layouts/page.html                                    |     1 |  0.57K | 0.000
_posts/2018-01-22-welcome-to-jekyll.markdown/#excerpt |     1 |  0.42K | 0.000
about.md                                              |     1 |  0.36K | 0.000
404.html                                              |     1 |  0.37K | 0.000
assets/main.scss                                      |     1 |  0.02K | 0.000
index.md                                              |     1 |  0.00K | 0.000

[ashmaroli]

current display when building with minima

Are you sure you have pulled the most recent commit, the output looks as expected on Travis

Filename                                              | Count |  Bytes |  Time
------------------------------------------------------+-------+--------+------
_posts/2018-02-09-welcome-to-jekyll.markdown          |     1 |  1.52K | 0.352
_layouts/default.html                                 |     4 | 22.34K | 0.089
minima-2.3.0/_includes/head.html                      |     4 |  7.26K | 0.049
feed.xml                                              |     1 |  3.62K | 0.019
minima-2.3.0/_includes/header.html                    |     4 |  5.38K | 0.018
minima-2.3.0/_includes/footer.html                    |     4 |  5.25K | 0.017
minima-2.3.0/_includes/social.html                    |     4 |  1.70K | 0.012
_layouts/home.html                                    |     1 |  0.46K | 0.003
_layouts/post.html                                    |     1 |  2.20K | 0.002
_layouts/page.html                                    |     1 |  0.67K | 0.000
_posts/2018-02-09-welcome-to-jekyll.markdown/#excerpt |     1 |  0.42K | 0.000
about.md                                              |     1 |  0.47K | 0.000
404.html                                              |     1 |  0.36K | 0.000
assets/main.scss                                      |     1 |  0.02K | 0.000
index.md                                              |     1 |  0.00K | 0.000

[DirtyF]

LGTM

[DirtyF]

@jekyllbot: merge +minor