[BUG] Tabulation causing error on `parse_file`

[felipemarkson]

Describe the bug The character UTF-8 0x09 (Tabulation) is not recognized in the parse_file using .dss files.

Minimum Viable Example

DSS Code

// test.dss
Clear
new	circuit.test	bus1=SOURCEBUS	pu=1.0
New	Line.Line_1	bus1=SOURCEBUS	bus2=BUS_1
New	Load.Load_1	phases=3	conn=Wye	bus1=BUS_1	kw=0.1	kvar=0.03	model=1
solve

Julia File

import PowerModelsDistribution
const PMD = PowerModelsDistribution

case_file = "test.dss"

model_dict = PMD.parse_file(case_file)

Screenshots

System Information (please complete the following information):

• OS: Manjaro Linux x86_64
• Version Kernel Linux 5.15.60-1-MANJARO

[felipemarkson]

I think that the problem is this function: https://github.com/lanl-ansi/PowerModelsDistribution.jl/blob/7a6b03eb0f96d0bcd3269b7d62ffda4d7ccaf4b0/src/io/dss/dss_parse.jl#L538

Because many of the validation statements use space. E.g.:

https://github.com/lanl-ansi/PowerModelsDistribution.jl/blob/7a6b03eb0f96d0bcd3269b7d62ffda4d7ccaf4b0/src/io/dss/dss_parse.jl#L554-L560

Maybe changing the space validation to the built-in Julia's function isspace can solve this issue.

@pseudocubic, I can create a PR if you are ok with this solution.

[pseudocubic]

@felipemarkson isspace looks like a promising solution, I would welcome the PR